Boardwalk Pipeline Partners (BWP) 10-K8 Feb 222021 FY Annual reportFinancial data

Company Profile

Document And Entity Information

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
Document And Entity Information - USD ($) $ in Millions	Dec. 31, 2021	Feb. 08, 2022	Jun. 30, 2021
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Document Transition Report	false
Entity File Number	01-32665
Entity Registrant Name	BOARDWALK PIPELINE PARTNERS, LP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-3265614
Entity Address, Address Line One	9 Greenway Plaza, Suite 2800
Entity Address, City or Town	Houston,
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77046
City Area Code	(866)
Local Phone Number	913-2122
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0001336047
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Common Stock, Shares Outstanding		0
Entity Public Float			$ 0

Audit Information

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2021
Audit Information [Abstract]
Auditor Name	Deloitte & Touche LLP
Auditor Firm ID	34
Auditor Location	Houston, Texas

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Current Assets:
Cash and cash equivalents	$ 39.1	$ 2.9
Receivables:
Trade, net	126.2	115.1
Other	31.4	23.4
Gas transportation receivables	8	6.6
Gas stored underground	26.1	2.8
Prepayments	21.4	18.5
Other current assets	7.1	4.2
Total current assets	259.3	173.5
Property, Plant and Equipment:
Natural gas transmission and other plant	12,248.6	11,964.1
Construction work in progress	239.5	184.2
Property, plant and equipment, gross	12,488.1	12,148.3
Less—accumulated depreciation and amortization	3,947	3,598.5
Property, plant and equipment, net	8,541.1	8,549.8
Other Assets:
Goodwill	237.4	237.4
Gas stored underground	114	101.9
Other	179.6	167.3
Total other assets	531	506.6
Total Assets	9,331.4	9,229.9
Payables:
Trade	31.1	43.6
Affiliates	1.7	9.9
Other	20.3	9.6
Gas transportation payables	20	10.9
Accrued taxes, other	65.8	70.3
Accrued interest	32.7	33.1
Accrued payroll and employee benefits	37.4	34.5
Construction retainage	16.6	11.5
Regulatory liabilities	12.7	14.1
Other current liabilities	21.4	29.4
Total current liabilities	259.7	266.9
Long-term debt and finance lease obligation	3,334.5	3,460.7
Other Liabilities and Deferred Credits:
Pension liability	5.6	18
Asset retirement obligations	61.5	54.9
Provision for other asset retirement	88.2	81.6
Other	112.8	98.7
Total other liabilities and deferred credits	268.1	253.2
Commitments and Contingencies
Partners' Capital:
Partners' capital	5,541.7	5,328.9
Accumulated other comprehensive loss	(72.6)	(79.8)
Total partners' capital	5,469.1	5,249.1
Total Liabilities and Partners' Capital	$ 9,331.4	$ 9,229.9

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Millions	12 Months Ended
CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Revenues:
Transportation	$ 1,152.6	$ 1,117.9	$ 1,146.2
Storage, parking and lending	110.4	110.5	92
Other	77.1	69.2	57
Total operating revenues	1,340.1	1,297.6	1,295.2
Operating Costs and Expenses:
Fuel and transportation	22.1	18.3	13.8
Operation and maintenance	226.9	212.3	219.1
Administrative and general	144.6	139.9	141.1
Depreciation and amortization	366.3	358.8	346.1
(Gain) loss on sale of assets and impairments	(0.1)	0.9	(3.2)
Taxes other than income taxes	113.2	112.8	104.6
Total operating costs and expenses	873	843	821.5
Operating income	467.1	454.6	473.7
Other Deductions (Income):
Interest expense	160.8	169.7	178.7
Interest income	0	0	(0.3)
Miscellaneous other income, net	(9.4)	(5.9)	(0.9)
Total other deductions	151.4	163.8	177.5
Income before income taxes	315.7	290.8	296.2
Income taxes	0.7	0.3	0.5
Net income	$ 315	$ 290.5	$ 295.7

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net income	$ 315	$ 290.5	$ 295.7
Other comprehensive income:
Reclassification adjustment transferred to Net income from cash flow hedges	0.9	0.8	0.9
Pension and other postretirement benefit costs, net of tax	6.3	0.5	3.2
Total Comprehensive Income	$ 322.2	$ 291.8	$ 299.8

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
OPERATING ACTIVITIES:
Net income	$ 315	$ 290.5	$ 295.7
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	366.3	358.8	346.1
Amortization of deferred costs and other	9	12.4	13.1
(Gain) loss on sale of assets and impairments	(0.1)	0.9	(3.2)
Changes in operating assets and liabilities:
Trade and other receivables	(19.1)	(6.1)	21.2
Gas transportation receivables and storage assets	(32.8)	(9)	(27.6)
Other assets	(2.7)	(4.5)	0.4
Trade and other payables	1.1	(10.6)	2.9
Gas transportation payables	9.3	1.4	(0.1)
Accrued liabilities	(1.3)	4.7	1.7
Regulatory assets and liabilities	(4.1)	4.8	20.7
Other liabilities	(11.3)	(2.1)	(8.9)
Net cash provided by operating activities	629.3	641.2	662
INVESTING ACTIVITIES:
Capital expenditures	(349.2)	(438.2)	(429)
Proceeds from sale of operating assets	1.7	3.8	5.7
Net cash used in investing activities	(347.5)	(434.4)	(423.3)
FINANCING ACTIVITIES:
Proceeds from long-term debt, net of issuance cost	0	495	495.2
Repayment of borrowings from long-term debt	0	(440)	(350)
Proceeds from borrowings on revolving credit facility	150	687.9	660
Repayment of borrowings on revolving credit facility, including financing fees	(284.4)	(852.9)	(945)
Principal payment of finance lease obligation	(0.8)	(0.7)	(0.7)
Advances from affiliates	(8.2)	5.3	4.1
Distributions paid	(102.2)	(102.2)	(102.2)
Net cash used in financing activities	(245.6)	(207.6)	(238.6)
Increase (decrease) in cash and cash equivalents	36.2	(0.8)	0.1
Cash and cash equivalents at beginning of period	2.9	3.7	3.6
Cash and cash equivalents at end of period	$ 39.1	$ 2.9	$ 3.7

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN PARTNERS' CAPITAL - USD ($) $ in Millions	Total	Accumulated Other Comprehensive Income (Loss)	Partners' Capital
Beginning Balance at Dec. 31, 2018	$ 4,861.9	$ (85.2)	$ 4,947.1
Add (deduct):
Net income	295.7		295.7
Distributions paid	(102.2)		(102.2)
Other comprehensive income, net of tax	4.1	4.1
Ending Balance at Dec. 31, 2019	5,059.5	(81.1)	5,140.6
Add (deduct):
Net income	290.5		290.5
Distributions paid	(102.2)		(102.2)
Other comprehensive income, net of tax	1.3	1.3
Ending Balance at Dec. 31, 2020	5,249.1	(79.8)	5,328.9
Add (deduct):
Net income	315		315
Distributions paid	(102.2)		(102.2)
Other comprehensive income, net of tax	7.2	7.2
Ending Balance at Dec. 31, 2021	$ 5,469.1	$ (72.6)	$ 5,541.7

Supplemental Disclosure of Cash

Supplemental Disclosure of Cash Flow Information	12 Months Ended
Supplemental Disclosure of Cash Flow Information	Dec. 31, 2021
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosure of Cash Flow Information	Supplemental Disclosure of Cash Flow Information (in millions): For the Year Ended December 31, 2021 2020 2019 Cash paid during the period for: Interest (net of amount capitalized) $ 152.2 $ 162.1 $ 171.5 Income taxes, net 0.5 0.6 0.3 Non-cash adjustments: Accounts payable and PPE 19.4 29.2 42.7 Right-of-use assets obtained in exchange for lease obligations 13.1 0.4 18.3

Supplemental Disclosure of Ca_2

Supplemental Disclosure of Cash Flow Information (Tables)	12 Months Ended
Supplemental Disclosure of Cash Flow Information (Tables)	Dec. 31, 2021
Supplemental Cash Flow Elements [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	Supplemental Disclosure of Cash Flow Information (in millions): For the Year Ended December 31, 2021 2020 2019 Cash paid during the period for: Interest (net of amount capitalized) $ 152.2 $ 162.1 $ 171.5 Income taxes, net 0.5 0.6 0.3 Non-cash adjustments: Accounts payable and PPE 19.4 29.2 42.7 Right-of-use assets obtained in exchange for lease obligations 13.1 0.4 18.3

Supplemental Disclosure of Ca_3

Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash paid during the period for:
Interest (net of amount capitalized)	$ 152.2	$ 162.1	$ 171.5
Income taxes, net	0.5	0.6	0.3
Non-cash adjustments:
Accounts payable and PPE	19.4	29.2	42.7
Right-of-use assets obtained in exchange for lease obligations	$ 13.1	$ 0.4	$ 18.3

Corporate Structure

Corporate Structure	12 Months Ended
Corporate Structure	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Corporate Structure	Corporate Structure Boardwalk Pipeline Partners, LP (the Company) is a Delaware limited partnership formed in 2005 to own and operate the business conducted by its primary subsidiary Boardwalk Pipelines, LP (Boardwalk Pipelines) and its operating subsidiaries, Gulf South Pipeline Company, LLC (Gulf South), Texas Gas Transmission, LLC (Texas Gas), Boardwalk Louisiana Midstream, LLC (Louisiana Midstream), Boardwalk Louisiana Gas Transmission, LLC (Louisiana Gas Transmission), Boardwalk Petrochemical Pipeline, LLC and Boardwalk Texas Intrastate, LLC (together, the operating subsidiaries), which consists of integrated pipeline and storage systems for natural gas and natural gas liquids and other hydrocarbons (herein referred to together as NGLs). All of the Company's operations are conducted by the operating subsidiaries. As of December 31, 2021, Boardwalk Pipelines Holding Corp. (BPHC), a wholly owned subsidiary of Loews Corporation (Loews), owned directly or indirectly, 100% of the Company's capital.

Basis of Presentation and Accou

Basis of Presentation and Accounting Policies	12 Months Ended
Basis of Presentation and Accounting Policies	Dec. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation and Accounting Policies	Basis of Presentation and Accounting Policies Basis of Presentation The accompanying consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP). Principles of Consolidation The consolidated financial statements include the Company's accounts and those of its wholly owned subsidiaries after elimination of intercompany transactions. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses and disclosure of contingent assets and liabilities and the fair values of certain items. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, which form the basis for making judgments about the carrying amounts of assets and liabilities that are not readily apparent from other sources. Actual results could differ from such estimates. Segment Information The Company operates in one reportable segment - the operation of interstate natural gas and NGLs pipeline systems and integrated storage facilities. This segment consists of interstate natural gas pipeline systems located in the Gulf Coast region, Oklahoma, Arkansas, Tennessee, Kentucky, Illinois, Indiana and Ohio and integrated natural gas storage facilities located in Indiana, Kentucky, Louisiana and Mississippi, and NGLs pipelines and storage facilities located in Louisiana and Texas. Regulatory Accounting Most of the Company's natural gas pipeline subsidiaries are regulated by the Federal Energy Regulatory Commission (FERC). When certain criteria are met, GAAP requires that certain rate-regulated entities account for and report assets and liabilities consistent with the economic effect of the manner in which independent third-party regulators establish rates (regulatory accounting). This basis of accounting is applicable to operations of the Company's Texas Gas subsidiary, which records certain costs and benefits as regulatory assets and liabilities in order to provide for recovery from or refunds to customers in future periods, but is not applicable to the operations associated with the Fayetteville and Greenville Laterals due to rates charged under negotiated rate agreements and a portion of Texas Gas' storage capacity due to the regulatory treatment associated with the rates charged for that capacity. The Company applies regulatory accounting for its fuel trackers on Gulf South, under which the value of fuel received from customers paying the maximum tariff rate and the related value of fuel used in transportation are recorded to a regulatory asset or liability depending on whether Gulf South uses more fuel than it collects from customers or collects more fuel than it uses. Other than as described for Texas Gas and for the fuel trackers on Gulf South, regulatory accounting is not applicable to the Company's other FERC-regulated operations. The Company monitors the regulatory and competitive environment in which it operates to determine whether its regulatory assets continue to be probable of recovery. If the Company determines that all or a portion of its regulatory assets no longer meets the criteria for recognition as regulatory assets, that portion which is not recoverable will be written off, net of any regulatory liabilities. Note 10 contains more information regarding the Company's regulatory assets and liabilities. Fair Value Measurements Fair value refers to an exit price that would be received to sell an asset or paid to transfer a liability in an orderly transaction in the principal market in which the reporting entity transacts based on the assumptions market participants would use when pricing the asset or liability assuming its highest and best use. A fair value hierarchy has been established that prioritizes the information used to develop those assumptions giving priority, from highest to lowest, to quoted prices in active markets for identical assets and liabilities (Level 1); observable inputs not included in Level 1, for example, quoted prices for similar assets and liabilities (Level 2); and unobservable data (Level 3), for example, a reporting entity's own internal data based on the best information available in the circumstances. The Company uses fair value measurements to account for asset retirement obligations (ARO) and any impairment charges. Notes 6 and 12 contain more information regarding fair value measurements. Cash and Cash Equivalents Cash equivalents are highly liquid investments with an original maturity of three months or less and are stated at cost plus accrued interest, which approximates fair value. The Company had no restricted cash at December 31, 2021 and 2020. Cash Management The operating subsidiaries participate in an intercompany cash management program, with those that are FERC-regulated participating to the extent they are permitted under FERC regulations. Under the cash management program, depending on whether a participating subsidiary has short-term cash surpluses or cash requirements, Boardwalk Pipelines either provides cash to them or they provide cash to Boardwalk Pipelines. The transactions are represented by demand notes and are stated at historical carrying amounts. Interest income and expense are recognized on an accrual basis when collection is reasonably assured. The interest rate on intercompany demand notes is London Interbank Offered Rate (LIBOR), or such benchmark replacement rate, plus 1.00% and is adjusted every three months. Trade and Other Receivables Trade and other receivables are stated at their historical carrying amount, net of allowances for doubtful accounts. The Company establishes an allowance for doubtful accounts under an expected credit loss model based on historical credit loss experience and specific facts and circumstances. Uncollectible receivables are written off when a settlement is reached for an amount that is less than the outstanding historical balance or a receivable amount is deemed otherwise unrealizable. Gas Stored Underground and Gas Receivables and Payables Certain of the Company's operating subsidiaries have underground gas in storage which is utilized for system management and operational balancing, as well as for services including firm and interruptible storage associated with certain no-notice and parking and lending (PAL) services. Gas stored underground includes the historical cost of natural gas volumes owned by the operating subsidiaries, at times reduced by certain operational encroachments upon that gas. The operating subsidiaries provide storage services whereby they store natural gas or NGLs on behalf of customers and also periodically hold customer gas under PAL services. Since the customers retain title to the gas held by the Company in providing these services, the Company does not record the related gas on its Consolidated Balance Sheets . Certain of the Company's operating subsidiaries also periodically lend gas and NGLs to customers. In the course of providing transportation and storage services to customers, the operating subsidiaries may receive different quantities of gas from shippers and operators than the quantities delivered on behalf of those shippers and operators. This results in transportation and exchange gas receivables and payables, commonly known as imbalances, which are primarily settled in cash or the receipt or delivery of gas in the future. Settlement of imbalances requires agreement between the pipelines and shippers or operators as to allocations of volumes to specific transportation contracts and timing of delivery of gas based on operational conditions. The receivables and payables are valued at market price for operations where regulatory accounting is not applicable and are valued at the historical value of gas in storage for operations where regulatory accounting is applicable. Materials and Supplies Materials and supplies are carried at average cost and are included in Other Assets on the Consolidated Balance Sheets. The Company expects its materials and supplies to be used for projects related to its property, plant and equipment (PPE) and for future growth projects. At December 31, 2021 and 2020, the Company held approximately $28.5 million and $25.5 million of materials and supplies. Property, Plant and Equipment and Repair and Maintenance Costs PPE is recorded at its original cost of construction or fair value of assets purchased. Construction costs and expenditures for major renewals and improvements which extend the lives of the respective assets are capitalized. Construction work in progress is included in the financial statements as a component of PPE. Repair and maintenance costs are expensed as incurred. Depreciation of PPE related to operations for which regulatory accounting does not apply is provided for using the straight-line method of depreciation over the estimated useful lives of the assets, which range from 3 to 35 years. The ordinary sale or retirement of PPE for these assets could result in a gain or loss being recorded in the income statement. Depreciation of PPE related to operations for which regulatory accounting is applicable is provided for primarily on the straight-line method at FERC-prescribed rates over estimated useful lives of 5 to 62 years. Reflecting the application of composite depreciation, gains and losses from the ordinary sale or retirement of PPE for these assets are not recognized in earnings and generally do not impact PPE, net. Note 7 contains more information regarding the Company's PPE. Goodwill and Intangible Assets Goodwill represents the excess of the cost of an acquisition over the fair value of the net identifiable assets acquired and liabilities assumed. Goodwill is tested for impairment at the reporting unit level at least annually, as of November 30, or more frequently when events occur and circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying amount. A reporting entity may perform an optional qualitative assessment on an annual basis to determine whether events occurred or circumstances changed that would more likely than not reduce the fair value of a reporting unit below its carrying amount. If an initial qualitative assessment identifies that it is more likely than not that the fair value of a reporting unit is less than its carrying amount, or the optional qualitative assessment is not performed, a quantitative analysis is performed. The quantitative goodwill impairment test is performed by calculating the fair value of the reporting unit and comparing it to the reporting unit's carrying amount. If the fair value of a reporting unit exceeds its carrying amount, goodwill of the reporting unit is not impaired. However, if the carrying amount of a reporting unit exceeds its fair value, an impairment loss is recognized in an amount equal to that excess, limited to the total amount of goodwill recorded on the reporting unit. Intangible assets are those assets which provide future economic benefit but have no physical substance. The Company recorded intangible assets for customer relationships obtained through its acquisitions. The customer relationships, which are included in Other Assets on the Consolidated Balance Sheets, have a finite life and are being amortized over their estimated useful lives. Note 8 contains more information regarding the Company's goodwill and intangible assets. Impairment of Long-lived Assets (including Tangible and Definite-lived Intangible Assets) The Company evaluates its long-lived and intangible assets for impairment when, in management's judgment, events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. When such a determination has been made, management's estimate of undiscounted future cash flows attributable to the remaining economic useful life of the asset (or asset group) is compared to the carrying amount of the asset (or asset group) to determine whether an impairment has occurred. If an impairment of the carrying amount has occurred, the amount of impairment recognized in the financial statements is determined by estimating the fair value of the assets (or asset group) and recording a loss to the extent that the carrying amount exceeds the estimated fair value. Capitalized Interest and Allowance for Funds Used During Construction (AFUDC) The Company records capitalized interest, which represents the cost of borrowed funds used to finance construction activities for operations where regulatory accounting is not applicable. The Company records AFUDC, which represents the cost of funds, including equity funds, applicable to regulated natural gas transmission plant under construction as permitted by FERC regulatory practices, in connection with the Company's operations where regulatory accounting is applicable. Capitalized interest and the allowance for borrowed funds used during construction are recognized as a reduction to Interest expense and the allowance for equity funds used during construction is included in Miscellaneous other income, net within the Consolidated Statements of Income. The following table summarizes capitalized interest and the allowance for borrowed funds and allowance for equity funds used during construction (in millions): For the Year Ended 2021 2020 2019 Capitalized interest and allowance for borrowed funds used during construction $ 3.8 $ 6.1 $ 5.6 Allowance for equity funds used during construction 7.9 4.1 1.5 Income Taxes The Company is not a taxable entity for federal income tax purposes. As such, it does not directly pay federal income tax. The Company's taxable income or loss, which may vary substantially from the net income or loss reported in the Consolidated Statements of Income, is includable in the federal income tax returns of each of its partners. The aggregate difference in the basis of the Company's net assets for financial and income tax purposes is $4.7 billion. The subsidiaries of the Company directly incur some income-based state taxes which are presented in Income taxes on the Consolidated Statements of Income. Note 13 contains more information regarding the Company's income taxes. Asset Retirement Obligations The accounting requirements for existing legal obligations associated with the future retirement of long-lived assets require entities to record the fair value of a liability for an ARO in the period during which the liability is incurred. The liability is initially recognized at fair value and is increased with the passage of time as accretion expense is recorded, until the liability is ultimately settled. The accretion expense is included within Operation and maintenance costs within the Consolidated Statements of Income. An amount corresponding to the amount of the initial liability is capitalized as part of the carrying amount of the related long-lived asset and depreciated over the useful life of that asset. Note 9 contains more information regarding the Company's ARO. Environmental Liabilities The Company records environmental liabilities based on management's estimates of the undiscounted future obligation for probable costs associated with environmental assessment and remediation of operating sites. These estimates are based on evaluations and discussions with counsel and operating personnel and the current known facts and circumstances related to these environmental matters. Note 5 contains more information regarding the Company's environmental liabilities. Defined Benefit Plans The Company maintains postretirement benefit plans for certain employees. The Company funds these plans through periodic contributions which are invested until the benefits are paid out to the participants, and records an asset or liability based on the overfunded or underfunded status of the plan. The net benefit costs of the plans are recorded in the Consolidated Statements of Income. Any deferred amounts related to unrecognized gains and losses or changes in actuarial assumptions are recorded as either a regulatory asset or liability or recorded as a component of accumulated other comprehensive income (AOCI) until those gains or losses are recognized in the Consolidated Statements of Income. Note 12 contains more information regarding the Company's pension and postretirement benefit obligations. Long-Term Compensation The Company provides performance awards (Performance Awards) to certain of its employees under its 2018 Long-Term Incentive Plan (2018 LTIP). A Performance Award is a long-term incentive award with a stated target amount which is payable in cash, after certain adjustments, upon vesting based on certain specified performance criteria being met. Prior to 2019, the Company provided awards of phantom common units (Phantom Common Units) to certain employees under its Long-Term Incentive Plan (LTIP) and awards of long-term cash bonuses (Long-Term Cash Bonuses) under the Boardwalk Pipeline Partners Unit Appreciation Rights (UAR) and Cash Bonus Plan. Since 2018, the Company has not granted awards in the form of Phantom Common Units or as Long-Term Cash Bonuses and as of December 31, 2020, all Phantom Common Units and Long-Term Cash Bonuses had vested and were paid. The Company measures the cost of an award issued in exchange for employee services based on the stated target amount for Performance Awards. All outstanding awards are required to be settled in cash and are classified as a liability until settlement. The related compensation expense, less forfeitures, is recognized over the period that employees are required to provide services in exchange for the awards, usually the vesting period. Note 12 contains more information regarding the Company's long-term compensation. Partner Capital Accounts For purposes of maintaining capital accounts, items of income and loss of the Company are allocated among the partners each period, or portion thereof, in accordance with the partnership agreement, based on their respective ownership interests. Leases Operating lease right-of-use assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. The discount rate used to determine the commencement date present value of lease payments is typically the Company's secured borrowing rate, as the implicit rate of most of the Company's leases is not readily determinable. The Company has elected not to record any leases with terms of twelve months or less on the Consolidated Balance Sheets. Revenue Recognition Nature of Contracts The Company primarily earns revenues from contracts with customers by providing transportation and storage services for natural gas and NGLs on a firm and interruptible basis. The Company also provides interruptible natural gas PAL services. The Company's customers choose, based upon their particular needs, the applicable mix of services depending upon availability of pipeline and storage capacity, the price of services and the volume and timing of customer requirements. The maximum rates that may be charged by the majority of the Company's operating subsidiaries are established through the FERC's cost-based rate-making process; however, rates actually charged by those operating subsidiaries may be less than those allowed by the FERC. Under the FERC regulations, certain revenues that the Company's subsidiaries collect may be subject to possible refunds to customers. Accordingly, during a rate case, estimated refund liabilities are recorded considering regulatory proceedings, advice of counsel and estimated risk-adjusted total exposure, as well as other factors. The Company's service contracts can range from one twenty ten thirty Firm Service Contracts : The Company offers firm services to its customers. The Company's customers can reserve a specific amount of pipeline capacity at specified receipt and delivery points on the Company's pipeline system (transportation service) or can reserve a specific amount of storage capacity at specified injection and withdrawal points at the Company's storage facilities (storage service). The Company accounts for firm services as a single promise to stand ready each month of the contract term to provide the committed capacity for either transportation or storage services when needed by the customer, which represents a series of distinct monthly services that are substantially the same with the same pattern of transfer to the customer. Although several activities may be required to provide the firm service, the individual activities do not represent distinct performance obligations because all of the activities must be performed in combination in order for the Company to provide the firm service. The transaction price for firm service contracts is comprised of a fixed fee based on the quantity of capacity reserved, regardless of use (capacity reservation fee), plus variable fees in the form of a usage fee paid on the volume of commodity actually transported or injected and withdrawn from storage. Both the fixed and usage fees are allocated to the single performance obligation of providing transportation or storage service and recognized over time based upon the output measure of time as the Company completes its stand-ready obligation to provide contracted capacity and the customer receives and consumes the benefit of the reserved capacity, which corresponds with the transfer of control to the customer. The fixed fee is recognized ratably over the contract term, representative of the proportion of the committed stand-ready capacity obligation that has been fulfilled to date, and the usage fee is recognized upon satisfaction of each distinct monthly performance obligation, consistent with the allocation objective and based upon the level of effort required to satisfy the stand-ready obligation in a given month. Capacity reservation revenues derived from a firm service contract are generally consistent during the contract term, but can be higher in winter periods than the rest of the year based upon seasonal rates. Interruptible Service Contracts : In providing interruptible services to customers, the Company agrees to transport or store natural gas or NGLs for a customer when capacity is available. The Company does not account for interruptible services with a customer as a contract until the customer nominates for service and the Company accepts the nomination based upon available pipeline or storage capacity because there are no enforceable rights and obligations until that time. The nomination and acceptance process is a daily activity and acceptance is granted based upon priority of service and availability of capacity. Upon acceptance, the Company accounts for interruptible services similarly to its firm services. The transaction price for interruptible service contracts is comprised of a variable fee in the form of a usage fee paid on the volume of commodity actually transported or injected and withdrawn from storage. The usage fee is allocated to the single performance obligation of providing interruptible service. Interruptible service revenues are generally recognized over time based on the output measure of volume transported or stored when services are rendered upon the successful allocation of the services provided to the customer's account, which best depicts the transfer of control to the customer and satisfaction of the promised service. Interruptible services are recognized in the month services are provided because the Company has a right to consideration from customers in amounts that correspond directly to the value that the customer receives from the Company's performance. The rates charged may vary on a daily, monthly or seasonal basis. Minimum Volume Commitment (MVC) Contracts : Certain of the Company's transportation or storage contracts require customers to transport or store a minimum volume of commodity over a specified time period. If a customer fails to meet its MVC for the specified time period, the customer is obligated to pay a contractually-determined deficiency fee based upon the shortfall between the actual volumes transported or stored and the MVC for that period. MVC contracts are similar in nature to a firm service contract where the performance obligation is a stand-ready obligation that is a series of distinct services that are substantially the same with the same pattern of transfer to the customer. The transaction price for an MVC is a fee for the volume of commodity actually transported or stored, which is allocated to each distinct monthly performance obligation, consistent with the allocation objective and based upon the level of effort required to satisfy the obligation of the transacted service in a given month. Revenues are generally recognized over time based on the output measure of volume transported or stored, with the recognition of the deficiency fee in the period when it is known the customer cannot make up the deficient volume in the specified period. Other : Periodically, the Company may enter into contracts with customers for the sale of natural gas or NGLs. The Company recognizes revenues for these transactions at the point in time of the physical sale of the commodity, which corresponds with the transfer of control of the commodity to the customer and the consideration is measured as the stated sales price in the contract. Contract Balances The Company records contract assets primarily related to performance obligations completed but not billed, or partially billed, as of the reporting date. The Company records contract liabilities, or deferred income, when payment is received in advance of satisfying its performance obligations.

Revenues

Revenues	12 Months Ended
Revenues	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenues from Contracts with Customers	Revenues The Company operates in one reportable segment and contracts directly with end-use customers, including local distribution companies, electric power generators, exporters of liquefied natural gas, and industrial users, with producers and marketers of natural gas, and with interstate and intrastate pipelines who, in turn, provide transportation and storage services for end-users. The following table presents the Company's revenues disaggregated by type of service for the years ended December 31, 2021, 2020 and 2019 (in millions): For the Year Ended December 31, 2021 2020 2019 Revenues from Contracts with Customers Firm Service (1) $ 1,247.5 $ 1,211.7 $ 1,228.3 Interruptible Service 32.0 33.2 29.0 Other revenues 26.1 18.9 9.1 Total Revenues from Contracts with Customers 1,305.6 1,263.8 1,266.4 Other operating revenues (2) 34.5 33.8 28.8 Total Operating Revenues $ 1,340.1 $ 1,297.6 $ 1,295.2 (1) Revenues earned from contracts with MVCs are included in firm service given the stand-ready nature of the performance obligation and the guaranteed nature of the fees over the contract term. The years ended December 31, 2020 and 2019, contain $34.4 million and $26.2 million of incremental revenues received related to customer bankruptcies as discussed in Note 5. (2) Other operating revenues include certain revenues earned from operating leases, pipeline management fees and other activities that are not considered central and ongoing major business operations of the Company and do not represent revenues earned from contracts with customers. Contract Balances As of December 31, 2021 and 2020, the Company had receivables recorded in Trade Receivables, net from contracts with customers of $126.2 million and $115.1 million, contract assets recorded in Other Assets from contracts with a customer of $2.3 million and $2.9 million, and contract liabilities recorded in Other current liabilities (current portion) and Other Liabilities (noncurrent portion) from contracts with customers of $19.2 million and $17.2 million. As of December 31, 2021, contract liabilities are expected to be recognized through 2040. Significant changes in the contract liability balances during the year ended December 31, 2021, are as follows (in millions): Contract Liabilities Balance as of December 31, 2020 (1) $ 17.2 Revenues recognized that were included in the contract liability (5.3) Increases due to cash received, excluding amounts recognized as 7.3 Balance as of December 31, 2021 (1) $ 19.2 (1) As of December 31, 2021 and 2020, $3.6 million a nd $4.9 million were recorded in Other current liabilities (current portion) and $15.6 million and $12.3 million were recorded in Other Liabilities (noncurrent portion). Significant changes in the contract liability balances during the year ended December 31, 2020, are as follows (in millions): Contract Liabilities Balance as of December 31, 2019 (1) $ 11.8 Revenues recognized that were included in the contract liability (5.1) Increases due to cash received, excluding amounts recognized as 10.5 Balance as of December 31, 2020 (1) $ 17.2 (1) As of December 31, 2020 and 2019, $4.9 million and $2.2 million were recorded in Other current liabilities (current portion) and $12.3 million and $9.6 million were recorded in Other Liabilities (noncurrent portion). Performance Obligations The following table includes estimated operating revenues expected to be recognized in the future related to agreements that contain performance obligations that were unsatisfied as of December 31, 2021. The amounts presented primarily consist of fixed fees or MVCs which are typically recognized over time as the performance obligation is satisfied, in accordance with firm service contracts. The Company's customers that are charged maximum tariff rates related to its FERC-regulated operating subsidiaries, the amounts below reflect the current tariff rate for such services for the term of the agreements; however, the tariff rates may be subject to future adjustment. The Company has elected to exclude the following from the table: (a) unsatisfied performance obligations from usage fees associated with its firm services because of the stand-ready nature of such services; (b) consideration in contracts that is recognized in revenue as invoiced, such as for interruptible services; and (c) consideration received prior to December 31, 2021, that will be recognized in revenue in future periods, such as the consideration recorded in contract liabilities. The estimated revenues reflected in the table may include estimated revenues that are anticipated under executed precedent transportation agreements for projects that are subject to regulatory approvals. In millions 2022 2023 Thereafter Total Estimated revenues from contracts with customers from unsatisfied performance obligations as of December 31, 2021 $ 1,115.0 $ 1,015.0 $ 6,704.5 $ 8,834.5 Operating revenues which are fixed and 25.0 25.0 175.5 225.5 Total projected operating revenues under committed firm agreements as of December 31, 2021 $ 1,140.0 $ 1,040.0 $ 6,880.0 $ 9,060.0

Leases

Leases	12 Months Ended
Leases	Dec. 31, 2021
Leases [Abstract]
Lessee, Finance Leases	Leases Operating lease right-of-use assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. The discount rate used to determine the commencement date present value of lease payments is typically the Company's secured borrowing rate, as the implicit rate of most of the Company's leases is not readily determinable. The components of lease cost were as follows (in millions): For the Year Ended December 31, 2021 2020 2019 Operating lease cost $ 4.0 $ 4.2 $ 4.3 Short-term lease cost 2.9 3.9 2.6 Finance lease cost: Amortization of right-of-use asset 0.7 0.7 0.7 Interest on lease liability 0.4 0.4 0.5 Total lease cost $ 8.0 $ 9.2 $ 8.1 The following provides supplemental balance sheet information related to the Company's leases: As of December 31, 2021 2020 Right-of-use assets (in millions) Operating leases (recorded in Other Assets ) $ 21.6 $ 11.8 Finance lease (recorded in Property, Plant and Equipment ) 4.7 5.4 Lease liabilities (in millions) Operating leases (recorded in Other Liabilities , current and non-current) 23.5 13.8 Finance lease 6.1 6.8 Weighted-average remaining lease term (years) Operating leases 10.8 3.8 Finance lease 6.6 7.6 Weighted-average discount rate Operating leases 2.94 % 4.72 % Finance lease 5.89 % 5.89 % The table below presents the maturities of lease liabilities (in millions): As of December 31, 2021 Operating Finance 2022 $ 3.7 $ 1.1 2023 3.8 1.1 2024 2.5 1.1 2025 2.2 1.1 2026 1.5 1.1 Thereafter 13.6 1.8 Total 27.3 7.3 Less: discount (3.8) (1.2) Total lease liabilities $ 23.5 $ 6.1
Lessee, Operating Leases	Leases Operating lease right-of-use assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. The discount rate used to determine the commencement date present value of lease payments is typically the Company's secured borrowing rate, as the implicit rate of most of the Company's leases is not readily determinable. The components of lease cost were as follows (in millions): For the Year Ended December 31, 2021 2020 2019 Operating lease cost $ 4.0 $ 4.2 $ 4.3 Short-term lease cost 2.9 3.9 2.6 Finance lease cost: Amortization of right-of-use asset 0.7 0.7 0.7 Interest on lease liability 0.4 0.4 0.5 Total lease cost $ 8.0 $ 9.2 $ 8.1 The following provides supplemental balance sheet information related to the Company's leases: As of December 31, 2021 2020 Right-of-use assets (in millions) Operating leases (recorded in Other Assets ) $ 21.6 $ 11.8 Finance lease (recorded in Property, Plant and Equipment ) 4.7 5.4 Lease liabilities (in millions) Operating leases (recorded in Other Liabilities , current and non-current) 23.5 13.8 Finance lease 6.1 6.8 Weighted-average remaining lease term (years) Operating leases 10.8 3.8 Finance lease 6.6 7.6 Weighted-average discount rate Operating leases 2.94 % 4.72 % Finance lease 5.89 % 5.89 % The table below presents the maturities of lease liabilities (in millions): As of December 31, 2021 Operating Finance 2022 $ 3.7 $ 1.1 2023 3.8 1.1 2024 2.5 1.1 2025 2.2 1.1 2026 1.5 1.1 Thereafter 13.6 1.8 Total 27.3 7.3 Less: discount (3.8) (1.2) Total lease liabilities $ 23.5 $ 6.1

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings and Settlements The Company and its subsidiaries are parties to various legal actions arising in the normal course of business. Management believes the disposition of these outstanding legal actions, including the legal actions identified below, will not have a material impact on the Company's financial condition, results of operations or cash flows. Mishal and Berger Litigation On May 25, 2018, plaintiffs Tsemach Mishal and Paul Berger (on behalf of themselves and the purported class, Plaintiffs) initiated a purported class action in the Court of Chancery of the State of Delaware (the Trial Court) against the following defendants: the Company, Boardwalk GP, LP (Boardwalk GP), Boardwalk GP, LLC and BPHC (together, Defendants), regarding the potential exercise by Boardwalk GP of its right to purchase the issued and outstanding common units of the Company not already owned by Boardwalk GP or its affiliates (Purchase Right). On June 25, 2018, Plaintiffs and Defendants entered into a Stipulation and Agreement of Compromise and Settlement, subject to the approval of the Trial Court (the Proposed Settlement). Under the terms of the Proposed Settlement, the lawsuit would be dismissed, and related claims against the Defendants would be released by the Plaintiffs, if BPHC, the sole member of the general partner of Boardwalk GP, elected to cause Boardwalk GP to exercise its Purchase Right for a cash purchase price, as determined by the Company's Third Amended and Restated Agreement of Limited Partnership, as amended (the Limited Partnership Agreement), and gave notice of such election as provided in the Limited Partnership Agreement within a period specified by the Proposed Settlement. On June 29, 2018, Boardwalk GP elected to exercise the Purchase Right and gave notice within the period specified by the Proposed Settlement. On July 18, 2018, Boardwalk GP completed the purchase of the Company's common units pursuant to the Purchase Right. On September 28, 2018, the Trial Court denied approval of the Proposed Settlement. On February 11, 2019, a substitute verified class action complaint was filed in this proceeding, which, among other things, added Loews as a Defendant. The Defendants filed a motion to dismiss, which was heard by the Trial Court in July 2019. In October 2019, the Trial Court ruled on the motion and granted a partial dismissal, with certain aspects of the case proceeding to trial. A trial was held the week of February 22, 2021, and post-trial oral arguments were held on July 14, 2021. On November 12, 2021, the Trial Court issued a ruling in the case. The Trial Court held that Boardwalk GP breached the Limited Partnership Agreement and found that Boardwalk GP is liable to the Plaintiffs for approximately $690.0 million in damages, plus pre-judgment interest (approximately $166.0 million), post-judgment interest and attorneys’ fees. The Trial Court’s ruling and damages award is against Boardwalk GP, and not the Company or its subsidiaries. The Defendants believe that the Trial Court ruling includes factual and legal errors. Therefore on January 3, 2022, the Defendants appealed the Trial Court’s ruling to the Supreme Court of the State of Delaware (the Supreme Court). On January 17, 2022, the Plaintiffs filed a cross-appeal to the Supreme Court contesting the calculation of damages by the Trial Court. City of New Orleans Litigation Gulf South, along with several other energy companies operating in Southern Louisiana, has been named as a defendant in a petition for damages and injunctive relief in state district court for Orleans Parish, Louisiana, (Case No. 19-3466) by the City of New Orleans. The case was filed on March 29, 2019. The lawsuit claims include, among other things, negligence, strict liability, nuisance and breach of contract, alleging that the defendants' drilling, dredging, pipeline and industrial operations since the 1930s have caused increased storm surge risk, increased flood protection costs and unspecified damages to the City of New Orleans. In October 2020, this case was stayed pending the outcome of a consolidated appeal to the 5th Circuit Court of Appeals in a similar case. On August 5, 2021, the 5th Circuit Court of Appeals ruled in favor of the oil-and-gas defendants in that consolidated appeal, finding that the two cases being appealed should be re-examined in federal district court since they involve operations that were federally overseen at the time. The ruling reverses a previous decision that allowed the cases to be heard in state court, which the plaintiffs had sought. As a result of the 5th Circuit Court of Appeals' decision, it is anticipated that this case will be reviewed in federal district court to determine whether the case should be heard in that court. Letter of Credit Proceeds In the fourth quarter 2020 and the second quarter 2019, two customers of Texas Gas declared bankruptcy and rejected the transportation agreements they had with Texas Gas as part of the bankruptcy proceedings. As a result, Texas Gas pursued and received proceeds from existing letters of credit provided to Texas Gas as credit support of $37.7 million from the 2020 bankruptcy and $27.7 million from the 2019 bankruptcy. In both cases, the bankruptcy courts approved the rejection of the transportation agreements, which relieved Texas Gas from providing further transportation services to those customers and allowed Texas Gas to remarket that capacity to other customers. Texas Gas first applied the proceeds from the letters of credit to any outstanding receivables related to the applicable customers and then recognized as transportation revenues the remaining $34.4 million of proceeds in December 2020 related to the 2020 bankruptcy and $26.2 million of proceeds in June 2019 related to the 2019 bankruptcy, which represent a portion of the future performance obligations that were eliminated under the transportation agreements. Environmental and Safety Matters The Company's operating subsidiaries are subject to federal, state and local environmental laws and regulations in connection with the operation and remediation of various operating sites. As of December 31, 2021 and 2020, the Company had an accrued liability of approximately $3.8 million and $4.2 million related to assessment and/or remediation costs associated with the historical use of polychlorinated biphenyls, petroleum hydrocarbons and mercury. The liability represents management's estimate of the undiscounted future obligations based on evaluations and discussions with counsel and operating personnel and the current known facts and circumstances related to these matters. The related expenditures are expected to occur over the next thirty years. As of December 31, 2021 and 2020, approximately $1.3 million and $1.0 million were recorded in Other current liabilities and approximately $2.5 million and $3.2 million were recorded in Other Liabilities and Deferred Credits . Clean Air Act and Climate Change The Company's pipelines and associated facilities are subject to the Clean Air Act (CAA) and comparable state laws and regulations, which regulate the emission of air pollutants from many sources and impose various compliance monitoring and reporting requirements. Under the CAA, the Company may be required to obtain pre-approval for the construction or modification of certain projects or facilities expected to produce or significantly increase air emissions, obtain and strictly comply with stringent air permit requirements or utilize specific equipment or technologies to control emissions. The need to obtain permits has the potential to delay the development or expansion of the Company's projects. Over the next several years, the Company may be required to incur certain capital expenditures for air pollution control equipment or other air emissions related issues. For example, in 2015, the Environmental Protection Agency (EPA) issued a final rule under the CAA, lowering the National Ambient Air Quality Standard (NAAQS) for ground-level ozone to 70 parts per billion under both the primary and secondary standards to provide requisite protection of public health and welfare, respectively. Since that time, the EPA issued area designations with respect to ground-level ozone, issued final requirements that apply to state, local and tribal air agencies for implementing the 2015 NAAQS for ground-level ozone and, on December 31, 2020, published notice of a final action to retain the 2015 ozone NAAQS without revision on a going-forward basis. However, several groups have filed litigation over this December 2020 final action, and the NAAQS may be subject to further revision under the Biden Administration. States are expected to implement more stringent regulations that could apply to the Company's operations. Compliance with this final rule could, among other things, require installation of new emission controls on some of the Company's equipment, result in longer permitting timelines and significantly increase its capital expenditures and operating costs. Additionally, the threat of climate change continues to attract considerable public, governmental and scientific attention. As a result, numerous proposals have been made and are likely to continue to be made at the international, national, regional, state and local levels of government to monitor and limit emissions of greenhouse gases (GHGs). These efforts have included consideration of cap-and-trade programs, carbon taxes, and GHG reporting and tracking programs, and regulations that directly limit GHG emissions from certain sources. The EPA has determined that GHG emissions endanger public health and the environment and, as a result, has adopted regulations under the CAA related to GHG emissions. Commitments for Construction The Company's future capital commitments are comprised of binding commitments under purchase orders for materials ordered but not received and firm commitments under binding construction service agreements. As of December 31, 2021, the commitments were approximately $95.3 million, all of which are expected to be settled within the next twelve months. Pipeline Capacity Agreements The Company's operating subsidiaries have entered into pipeline capacity agreements with third-party pipelines that allow the operating subsidiaries to transport gas to off-system markets on behalf of customers. The Company incurred expenses of $5.9 million, $4.2 million and $3.8 million related to pipeline capacity agreements for the years ended December 31, 2021, 2020 and 2019. The future commitments related to pipeline capacity agreements as of December 31, 2021, were $2.7 million in 2022, with no future commitments after 2022.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
Fair Value Measurements	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Financial Assets and Liabilities As of December 31, 2021 and 2020, the Company had no assets and liabilities which were recorded at fair value on a recurring basis. The following methods and assumptions were used in estimating the fair value amounts included in the disclosures for financial assets and liabilities: Cash and Cash Equivalents: For cash and short-term financial assets, the carrying amount is a reasonable estimate of fair value due to the short maturity of those instruments. Long-Term Debt: The estimated fair value of the Company's publicly traded debt is based on quoted market prices at December 31, 2021 and 2020. The fair market value of the debt that is not publicly traded is based on market prices of similar debt at December 31, 2021 and 2020. The carrying amount of the Company's variable-rate debt at December 31, 2021 and 2020, approximated fair value because the instruments bear a floating market-based interest rate. The carrying amounts and estimated fair values of the Company's financial assets and liabilities which were not recorded at fair value on the Consolidated Balance Sheets as of December 31, 2021 and 2020, were as follows (in millions): As of December 31, 2021 Estimated Fair Value Financial Assets Carrying Amount Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 39.1 $ 39.1 $ — $ — $ 39.1 Financial Liabilities Long-term debt $ 3,334.0 (1) $ — $ 3,631.5 $ — $ 3,631.5 (1) The carrying amount of long-term debt excludes a $5.3 million long-term finance lease obligation and $4.8 million of unamortized debt issuance costs. As of December 31, 2020 Estimated Fair Value Financial Assets Carrying Amount Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 2.9 $ 2.9 $ — $ — $ 2.9 Financial Liabilities Long-term debt $ 3,460.4 (1) $ — $ 3,847.6 $ — $ 3,847.6 (1) The carrying amount of long-term debt excludes a $6.1 million long-term finance lease obligation and $5.8 million of unamortized debt issuance costs.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
Property, Plant and Equipment	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment The following table presents the Company's PPE as of December 31, 2021 and 2020 (in millions): Category 2021 Weighted-Average 2020 Weighted-Average Depreciable plant: Transmission $ 10,672.7 37 $ 10,417.9 37 Storage 886.5 38 863.5 38 Gathering 109.6 23 108.0 23 General 228.6 15 224.9 14 Rights of way and other 153.7 33 153.2 33 Total utility depreciable plant 12,051.1 37 11,767.5 37 Non-depreciable: Construction work in progress 239.5 184.2 Storage 152.3 152.3 Land 45.2 44.3 Total non-depreciable assets 437.0 380.8 Total PPE 12,488.1 12,148.3 Less: accumulated depreciation 3,947.0 3,598.5 Total PPE, net $ 8,541.1 $ 8,549.8 The non-depreciable assets were not included in the calculation of the weighted-average useful lives. For each of the years ended December 31, 2021, 2020 and 2019, depreciation expense for PPE was $364.4 million, $356.9 million and $344.2 million and was recorded in Depreciation and amortization on the Consolidated Statements of Income. The Company holds undivided interests in certain assets, including the Mobile Bay Pipeline of which the Company owns 64% and offshore and other assets, comprised of pipeline and gathering assets in which the Company holds various ownership interests. In addition, the Company owns 83% of two ethylene wells and supporting surface facilities in Choctaw, Louisiana, and certain ethylene and propylene pipelines connecting Louisiana Midstream's storage facilities in Choctaw to chemical manufacturing plants in Geismar, Louisiana. The proportionate share of investment associated with these interests has been recorded as PPE on the Consolidated Balance Sheets. The Company records its portion of direct operating expenses associated with the assets in Operation and maintenance expense. The following table presents the gross PPE investment and related accumulated depreciation for the Company's undivided interests as of December 31, 2021 and 2020 (in millions): 2021 2020 Gross PPE Accumulated Depreciation Gross PPE Accumulated Depreciation Mobile Bay Pipeline $ 14.6 $ 7.5 $ 14.5 $ 7.1 NGLs pipelines and facilities 51.3 10.4 42.5 8.8 Offshore and other assets 12.8 10.4 12.8 10.1 Total $ 78.7 $ 28.3 $ 69.8 $ 26.0 Asset Purchases In September 2021, the Company, through its newly created operating subsidiary, Louisiana Gas Transmission, acquired certain natural gas pipeline assets in the Lake Charles, Louisiana, area for approximately $20.0 million in cash. In 2019, the Company entered into an agreement, subject to regulatory approval, to purchase the approximately 8% undivided interest that it did not already own in the Bistineau storage facility in Louisiana for approximately $18.8 million in cash. The FERC approved the purchase in early 2020 and the transaction closed on April 1, 2020. After this transaction, the Company owns 100% of the Bistineau storage facility.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
Goodwill and Intangible Assets	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill As of December 31, 2021 and 2020, the Company had recorded on its Consolidated Balance Sheets $237.4 million of goodwill. As of November 30, 2021, the Company elected to perform a qualitative assessment for its annual goodwill impairment test of its two reporting units. The qualitative assessment included the Company’s consideration of, among other things, the overall macroeconomic conditions, industry and market considerations, current discount rates and valuation multiples, overall financial performance and other relevant company specific events. Based on the assessment of these items, the Company concluded that it is more likely than not that the fair value of the two reporting units exceeded their respective carrying amounts. Accordingly, there were no indicators of impairment and the quantitative impairment test was not performed. As of November 30, 2020, the Company performed a quantitative annual goodwill impairment test for its two reporting units. The results of the quantitative goodwill impairment test indicated that the fair value of the Company's reporting units exceeded their carrying amounts. The fair value measurement of the reporting units was derived based on judgments and assumptions the Company believes market participants would use in assessing the fair value of the reporting units. These judgments and assumptions included the valuation premise, use of a discounted cash flow model to estimate fair value under an income approach and inputs to the valuation model. The inputs included the Company’s five-year financial plan operating results, including operating revenues, the long-term outlook for growth in natural gas and NGLs demand, measures of the risk-free rate, equity premium and systematic risk used in the calculation of the applied discount rate under the capital asset pricing model and views regarding future market conditions, among others. The reasonableness of fair value estimates under the income approach were supported by a market approach under which the Company applied EBITDA multiples derived from publicly-available information to each reporting unit's EBITDA. No impairment charges related to goodwill were recorded for any of the Company's reporting units during 2021, 2020 or 2019. Intangible Assets The following table contains information regarding the Company's intangible assets, which includes customer relationships acquired as part of its acquisitions (in millions): As of December 31, 2021 2020 Gross carrying amount $ 59.4 $ 59.4 Accumulated amortization (17.2) (15.3) Net carrying amount $ 42.2 $ 44.1 For each of the years ended December 31, 2021, 2020 and 2019, amortization expense for intangible assets was $1.9 million and was recorded in Depreciation and amortization on the Consolidated Statements of Income. Amortization expense for the next five years and in total thereafter as of December 31, 2021, is expected to be as follows (in millions): 2022 $ 1.9 2023 1.9 2024 2.0 2025 2.0 2026 2.0 Thereafter 32.4 Total $ 42.2 The weighted-average remaining useful life of the Company's intangible assets as of December 31, 2021, was 22 years.

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
Asset Retirement Obligations	Dec. 31, 2021
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations The Company has identified and recorded legal obligations associated with the abandonment of certain pipeline and storage assets, brine ponds, offshore facilities and the abatement of asbestos consisting of removal, transportation and disposal when removed from certain compressor stations and meter station buildings. Legal obligations exist for the main pipeline and certain other Company assets; however, the fair value of these obligations cannot be determined because the lives of the assets are indefinite. As a result, cash flows associated with retirement of the assets cannot be estimated with the degree of accuracy necessary to establish a liability for the obligations. The following table summarizes the aggregate carrying amount of the Company's ARO as of December 31, 2021 and 2020 (in millions): 2021 2020 Balance at beginning of year $ 63.1 $ 60.4 Liabilities recorded 9.5 1.3 Liabilities settled (2.2) (0.9) Accretion expense 2.9 2.3 Revision of estimates (8.4) — Balance at end of year 64.9 63.1 Less: Current portion of ARO (3.4) (8.2) Long-term ARO $ 61.5 $ 54.9 For the Company's operations where regulatory accounting is applicable, depreciation rates for PPE are comprised of two components. One component is based on economic service life (capital recovery) and the other is based on estimated costs of removal (as a component of negative salvage) which is collected in rates and does not represent an existing legal obligation. The Company has reflected $88.2 million and $81.6 million as of December 31, 2021 and 2020, on the Consolidated Balance Sheets as Provision for other asset retirement related to the estimated cost of removal collected in rates.

Regulatory Assets and Liabiliti

Regulatory Assets and Liabilities	12 Months Ended
Regulatory Assets and Liabilities	Dec. 31, 2021
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets and Liabilities	Regulatory Assets and Liabilities The amounts recorded as regulatory assets and liabilities on the Consolidated Balance Sheets as of December 31, 2021 and 2020, are summarized in the table below. The table also includes amounts related to unamortized debt issuance costs and unamortized discount on long-term debt, which while not regulatory assets and liabilities, are a critical component of the embedded cost of debt financing utilized in Texas Gas' rate proceedings. The tax effect of the equity component of AFUDC represents amounts recoverable from rate payers for the tax recorded in regulatory accounting. Certain amounts in the table are reflected as a negative, or a reduction, to be consistent with the regulatory books of account. The period of recovery for the regulatory assets included in rates varies from one eighteen yet included in rates would be determined in future rate proceedings. None of the regulatory assets shown below were earning a return as of December 31, 2021 and 2020 (in millions): 2021 2020 Regulatory Assets: Pension $ 8.1 $ 10.6 Tax effect of AFUDC equity 0.4 0.6 Fuel tracker 6.8 4.2 Other 0.5 0.5 Total regulatory assets $ 15.8 $ 15.9 Regulatory Liabilities: Cashout and fuel tracker $ 12.7 $ 14.1 Provision for other asset retirement 88.2 81.6 Unamortized debt issuance costs (1.5) (1.8) Unamortized discount on long-term debt (0.2) (0.2) Postretirement benefits other than pension 64.7 63.3 Total regulatory liabilities $ 163.9 $ 157.0

Financing

Financing	12 Months Ended
Financing	Dec. 31, 2021
Debt Disclosure [Abstract]
Financing	Financing Long-Term Debt The following table presents all long-term debt issuances outstanding as of December 31, 2021 and 2020 (in millions): 2021 2020 Notes and Debentures: Boardwalk Pipelines 3.375% Notes due 2023 $ 300.0 $ 300.0 4.95% Notes due 2024 600.0 600.0 5.95% Notes due 2026 550.0 550.0 4.45% Notes due 2027 500.0 500.0 4.80% Notes due 2029 500.0 500.0 3.40% Notes due 2031 500.0 500.0 Gulf South 4.00% Notes due 2022 (Gulf South Notes) 300.0 300.0 Texas Gas 7.25% Debentures due 2027 100.0 100.0 Total notes and debentures 3,350.0 3,350.0 Revolving Credit Facility: Gulf South — 30.0 Texas Gas — 100.0 Total revolving credit facility — 130.0 Finance lease obligation 5.3 6.1 3,355.3 3,486.1 Less: Unamortized debt discount (16.0) (19.6) Unamortized debt issuance costs (4.8) (5.8) Total Long-Term Debt and Finance Lease Obligation $ 3,334.5 $ 3,460.7 Maturities of the Company's long-term debt for the next five years and in total thereafter are as follows (in millions): 2022 $ 300.0 2023 300.0 2024 600.0 2025 — 2026 550.0 Thereafter 1,600.0 Total long-term debt $ 3,350.0 The Company has included the Gulf South Notes which mature in less than one year as long-term debt on its Consolidated Balance Sheets as of December 31, 2021. The Company has the intent and the ability to refinance the notes through the available borrowing capacity under its revolving credit facility as of December 31, 2021. Notes and Debentures As of December 31, 2021 and 2020, the weighted-average interest rate of the Company's notes and debentures was 4.84%. The Company had no new debt issuances for the year ended December 31, 2021. For the years ended December 31, 2020 and 2019, the Company completed the following debt issuances (in millions, except interest rates): Date of Issuing Subsidiary Amount of Purchaser Net Interest Maturity Date Interest August 2020 Boardwalk Pipelines $ 500.0 $ 5.0 $ 495.0 (1) 3.40 % February 15, 2031 February 15 and August 15 May 2019 Boardwalk Pipelines $ 500.0 $ 4.8 $ 495.2 (2) 4.80 % May 3, 2029 May 3 and November 3 (1) The net proceeds of this offering were used to retire the outstanding $440.0 million aggregate principal amount of Texas Gas 4.50% notes due 2021 on November 3, 2020, to fund growth capital expenditures and for general partnership purposes. (2) The net proceeds of this offering were used to retire the outstanding $350.0 million aggregate principal amount of Boardwalk Pipelines 5.75% notes due 2019 at maturity and for general partnership purposes. The Company's notes and debentures are redeemable, in whole or in part, at the Company's option at any time, at a redemption price equal to the greater of 100% of the principal amount of the notes to be redeemed or a “make whole” redemption price based on the remaining scheduled payments of principal and interest discounted to the date of redemption at a rate equal to the Treasury rate plus 20 to 50 basis points depending upon the particular issue of notes, plus accrued and unpaid interest, if any. Other customary covenants apply, including those concerning events of default. The indentures governing the notes and debentures have restrictive covenants which provide that, with certain exceptions, neither the Company nor any of its subsidiaries may create, assume or suffer to exist any lien upon any property to secure any indebtedness unless the debentures and notes shall be equally and ratably secured. All of the Company's debt obligations are unsecured. As of December 31, 2021, Boardwalk Pipelines and its operating subsidiaries were in compliance with their debt covenants. Revolving Credit Facility In May 2021, the Company entered into a Master Assignment and Amendment No. 3 to Third Amended and Restated Revolving Credit Agreement (the Amendment), which amended the Third Amended and Restated Revolving Credit Agreement, dated May 26, 2015 (as amended and modified, the Credit Agreement). The Credit Agreement includes Boardwalk Pipelines, Texas Gas and Gulf South as borrowers (Borrowers). Interest is determined, at the Company's election, by reference to (a) the base rate which is the highest of (1) the prime rate, (2) the federal funds rate plus 0.50% and (3) the one month Eurodollar Rate plus 1.00%, plus an applicable margin, or (b) the one-month LIBOR (or such benchmark replacement rate as defined in the Credit Agreement) plus an applicable margin. The applicable margin ranges from 0.00% to 0.75% for loans bearing interest based on the base rate and ranges from 1.00% to 1.75% for loans bearing interest based on the LIBOR rate, in each case determined based on the individual Borrower's credit rating from time to time. The Credit Agreement provides for a quarterly commitment fee charged on the average daily unused amount of the revolving credit facility ranging from 0.10% to 0.275% which is determined based on the individual Borrower's credit rating from time to time. The revolving credit facility provided under the Credit Agreement has a borrowing capacity of $1.0 billion through May 27, 2026, with two one-year extensions at the Company's election. The Credit Agreement contains various restrictive covenants and other usual and customary terms and conditions, including restrictions regarding the incurrence of additional debt, the sale of assets and sale-leaseback transactions. The financial covenants under the Credit Agreement require the Company and its subsidiaries to maintain, among other things, a ratio of total consolidated debt to consolidated EBITDA (as defined in the Credit Agreement) measured for the previous twelve months of not more than 5.0 to 1.0, or up to 5.5 to 1.0 for (i) the quarter in which the consummation of a qualified acquisition or series of acquisitions, where the purchase price exceeds $100.0 million over a rolling 12-month period and (ii) the three quarters following the qualified acquisition quarter. The Company and its subsidiaries were in compliance with all covenant requirements under the Credit Agreement as of December 31, 2021. As of December 31, 2021, and February 4, 2022, the Company had no outstanding borrowings and all of the $1.0 billion available borrowing capacity under the revolving credit facility. Outstanding borrowings under the Company's revolving credit facility as of December 31, 2020, were $130.0 million, with a weighted-average borrowing rate of 1.39%. Cash Distributions For each of the years ended December 31, 2021, 2020 and 2019, the Company paid cash distributions of $102.2 million to its partners as determined by Boardwalk GP.

Employee Benefits

Employee Benefits	12 Months Ended
Employee Benefits	Dec. 31, 2021
Retirement Benefits [Abstract]
Employee Benefits	Employee Benefits Retirement Plans Defined Benefit Retirement Plans (Retirement Plans) Texas Gas employees hired prior to November 1, 2006, are covered under a non-contributory, defined benefit pension plan (Pension Plan). The Texas Gas Supplemental Retirement Plan (SRP) provides pension benefits for the portion of an eligible employee's pension benefit under the Pension Plan that becomes subject to compensation limitations under the Internal Revenue Code. Collectively, the Company refers to the Pension Plan and the SRP as Retirement Plans. The Company uses a measurement date of December 31 for the Retirement Plans. As a result of the Texas Gas rate case settlement in 2006, the Company is required to fund the amount of annual net periodic pension cost associated with the Pension Plan, including a minimum of $3.0 million, which is the amount included in rates. In 2021 and 2020, the Company funded $5.2 million and $3.6 million to the Pension Plan and expects to fund an additional $3.0 million to the plan in 2022. In 2021 and 2020, there were no payments made to the SRP. The Company recognizes in expense each year the actuarially determined amount of net periodic pension cost associated with the Retirement Plans, including a minimum amount of $3.0 million related to its Pension Plan, in accordance with the 2006 rate case settlement. Texas Gas is permitted to seek future rate recovery for amounts of annual Pension Plan costs in excess of $6.0 million and is precluded from seeking future recovery of annual Pension Plan costs between $3.0 million and $6.0 million. As a result, the Company would recognize a regulatory asset for amounts of annual Pension Plan costs in excess of $6.0 million and would reduce its regulatory asset to the extent that annual Pension Plan costs are less than $3.0 million. Annual Pension Plan costs between $3.0 million and $6.0 million will be charged to expense. Postretirement Benefits Other Than Pension (PBOP) Texas Gas provides postretirement medical benefits and life insurance to retired employees who were employed full time, hired prior to January 1, 1996, and have met certain other requirements. In each of 2021 and 2020, the Company contributed $0.1 million to the PBOP plan. The PBOP plan is in an overfunded status; therefore, the Company does not expect to make any contributions to the plan in 2022. The Company does not anticipate that any plan assets will be returned to the Company during 2022. The Company uses a measurement date of December 31 for its PBOP plan. Projected Benefit Obligation, Fair Value of Assets and Funded Status The projected benefit obligation, fair value of assets, funded status and the amounts not yet recognized as components of net periodic pension and postretirement benefits cost for the Retirement Plans and PBOP at December 31, 2021 and 2020, were as follows (in millions): Retirement Plans PBOP For the Year Ended For the Year Ended 2021 2020 2021 2020 Change in benefit obligation: Benefit obligation at beginning of period $ 120.7 $ 122.2 $ 35.2 $ 36.5 Service cost 2.6 2.8 0.1 0.1 Interest cost 2.1 2.7 0.9 1.1 Plan participants' contributions — — 1.1 1.1 Actuarial (gain) loss (1.4) 6.0 (2.6) (0.3) Benefits paid (0.5) (0.5) (4.1) (3.3) Settlements (14.4) (12.5) — — Benefit obligation at end of period $ 109.1 $ 120.7 $ 30.6 $ 35.2 Change in plan assets: Fair value of plan assets at beginning of period $ 102.7 $ 101.7 $ 96.2 $ 90.8 Actual return on plan assets 10.5 10.4 (0.3) 7.5 Company's contribution 5.2 3.6 0.1 0.1 Plan participants' contributions — — 1.1 1.1 Benefits paid (0.5) (0.5) (4.1) (3.3) Settlements (14.4) (12.5) — — Fair value of plan assets at end of period $ 103.5 $ 102.7 $ 93.0 $ 96.2 Funded status $ (5.6) $ (18.0) $ 62.4 $ 61.0 Items not recognized as components of net periodic cost: Net actuarial loss (gain) $ 10.0 $ 18.2 $ (2.9) $ (3.4) At December 31, 2021 and 2020, the following aggregate information relates only to the underfunded plans (in millions): Retirement Plans For the Year Ended 2021 2020 Projected benefit obligation $ 109.1 $ 120.7 Accumulated benefit obligation 103.4 113.7 Fair value of plan assets 103.5 102.7 Components of Net Periodic Benefit Cost Components of net periodic benefit cost for both the Retirement Plans and PBOP for the years ended December 31, 2021, 2020 and 2019, were as follows (in millions): Retirement Plans PBOP For the Year Ended For the Year Ended 2021 2020 2019 2021 2020 2019 Service cost $ 2.6 $ 2.8 $ 3.0 $ 0.1 $ 0.1 $ 0.1 Interest cost 2.1 2.7 3.9 0.9 1.1 1.4 Expected return on plan assets (6.2) (6.3) (6.4) (2.7) (3.2) (3.0) Amortization of unrecognized net loss 0.8 1.9 2.2 — — — Settlement charge 1.6 2.4 2.9 — — — Regulatory asset decrease 2.5 — — — — — Net periodic benefit cost $ 3.4 $ 3.5 $ 5.6 $ (1.7) $ (2.0) $ (1.5) Due to the Texas Gas rate case settlement in 2006, Texas Gas is permitted to seek future rate recovery for amounts of annual Pension Plan costs in excess of $6.0 million. Estimated Future Benefit Payments The following table shows benefit payments, which reflect expected future service, as appropriate, which are expected to be paid for both the Retirement Plans and PBOP (in millions): Retirement Plans PBOP 2022 $ 21.8 $ 2.1 2023 11.9 2.1 2024 10.7 2.0 2025 11.9 1.9 2026 10.1 1.9 2027-2031 34.5 7.5 Weighted-Average Assumptions Weighted-average assumptions used to determine benefit obligations for the years ended December 31, 2021 and 2020, were as follows: Retirement Plans PBOP For the Year Ended For the Year Ended 2021 2020 2021 2020 Pension SRP Pension SRP Discount rate 2.30 % 2.35 % 1.70 % 1.55 % 2.90 % 2.60 % Expected return on plan assets 6.25 % 6.25 % 6.50 % 6.50 % 2.01 % 2.81 % Rate of compensation increase 3.00 % 3.00 % 3.00 % 3.00 % — — Weighted-average assumptions used to determine net periodic benefit cost for the periods indicated were as follows: Retirement Plans PBOP For the Year Ended For the Year Ended 2021 2020 2019 2021 2020 2019 Pension SRP Pension SRP Pension SRP Discount rate (1) 1.55 % (1) 2.70 % (1) 4.10 % 2.60 % 3.30 % 4.30 % Expected return on plan assets 6.50% 6.50 % 7.00% 7.00 % 7.00% 7.00 % 2.81 % 3.61 % 3.61 % Rate of compensation increase 3.00% 3.00 % 3.00% 3.00 % 3.86% 3.86 % — — — (1) Pension expense was remeasured quarterly in 2021, 2020 and 2019. The quarterly remeasurements for each quarter in 2021, 2020 and 2019 were as follows: Quarter 1: 2.05%, 2.95% and 3.80%; Quarter 2: 2.05%, 2.20% and 3.25%; Quarter 3: 1.95%, 1.85% and 2.60%; and Quarter 4: 2.30%, 1.70% and 2.70%. In determining the discount rate assumption, current market and liability information is utilized, including a discounted cash flow analysis of the pension and postretirement obligations. In particular, the basis for the discount rate selection was the yield on indices of highly rated fixed income debt securities with durations comparable to that of the Company's plan liabilities. The yield curve was applied to expected future retirement plan payments to adjust the discount rate to reflect the cash flow characteristics of the plans. The yield curves and indices evaluated in the selection of the discount rate are comprised of high-quality corporate bonds that are rated AA by an accepted rating agency. The expected long-term rate of return for plan assets was determined based on widely-accepted capital market principles, long-term return analysis for global fixed income and equity markets as well as the active total return oriented portfolio management style. Long-term trends are evaluated relative to market factors such as inflation, interest rates and fiscal and monetary policies, in order to assess the capital market assumptions as applied to the plan. Consideration of diversification needs and rebalancing is maintained. Pension Plan and PBOP Asset Allocation and Investment Strategy Pension Plan The Pension Plan investments are held in a trust account and consist of an undivided interest in an investment account of the Loews Corporation Employees Retirement Trust (Master Trust), established by Loews and its participating subsidiaries. Use of the Master Trust permits the co-investing of trust assets of the Pension Plan with the assets of the Loews Corporation Cash Balance Retirement Plan for investment and administrative purposes. Although assets of all plans are co-invested in the Master Trust, the custodian maintains supporting records for the purpose of allocating the net gain or loss of the investment account to the participating plans. The net investment income of the investment assets is allocated by the custodian to each participating plan based on the relationship of the interest of each plan to the total of the interests of the participating plans. The Master Trust assets are measured at fair value. The fair value of the interest in the assets of the Master Trust associated with the Pension Plan as of December 31, 2021 and 2020, was $103.5 million (or 43.2%) and $102.7 million (or 43.9%), of the total Master Trust assets. Equity securities are publicly traded securities which are valued using quoted market prices and are considered a Level 1 investment under the fair value hierarchy. Short-term and other asset investments that are actively traded or have quoted prices, such as money market funds or treasury bills, are considered Level 1 investments. Fixed income mutual funds include highly liquid government securities and exchange traded bonds, valued using quoted market prices, and are considered a Level 1 investment. The limited partnership investments held within the Master Trust are recorded at fair value, which represents the Master Trust's shares of the net asset value of each partnership, as determined by the general partner. The limited partnership and other invested assets consist primarily of hedge fund strategies that generate returns through investing in marketable securities in the public fixed income and equity markets. The following table sets forth, by level within the fair value hierarchy, a summary of the Master Trust's investments measured at fair value on a recurring basis at December 31, 2021 (in millions): Master Trust Assets Measured under Fair Value Hierarchy Measured at Net Asset Value Total Master Trust Assets Level 1 Level 2 Level 3 Total Equity securities $ 69.1 $ — $ — $ 69.1 $ — $ 69.1 Short-term investments 1.9 — — 1.9 — 1.9 Other assets 2.2 — — 2.2 — 2.2 Fixed income mutual funds 111.3 — — 111.3 — 111.3 Total assets measured at fair 184.5 — — 184.5 — 184.5 Total limited partnerships — — — — 54.9 54.9 Total $ 184.5 $ — $ — $ 184.5 $ 54.9 $ 239.4 The following table sets forth, by level within the fair value hierarchy, a summary of the Master Trust's investments measured at fair value on a recurring basis at December 31, 2020 (in millions): Master Trust Assets Measured under Fair Value Hierarchy Measured at Net Asset Value Total Master Trust Assets Level 1 Level 2 Level 3 Total Equity securities $ 59.9 $ — $ — $ 59.9 $ — $ 59.9 Short-term investments 3.9 — — 3.9 — 3.9 Fixed income mutual funds 112.5 — — 112.5 — 112.5 Total assets measured at fair 176.3 — — 176.3 — 176.3 Total limited partnerships — — — — 57.5 57.5 Total $ 176.3 $ — $ — $ 176.3 $ 57.5 $ 233.8 PBOP The PBOP plan assets are held in a trust and are measured at fair value. Short-term investments that are actively traded or have quoted prices, such as money market or mutual funds, are considered Level 1 investments. Fixed income mutual funds are actively traded and valued using quoted market prices and are considered Level 1 investments. Tax exempt securities, consisting of municipal securities, corporate and other taxable bonds and asset-backed securities are valued using a methodology based on information generated by market transactions involving identical or comparable assets, a discounted cash flow methodology or a combination of both when necessary. Common inputs for tax exempt securities include pricing for similar securities, marketplace quotes, benchmark yields, spreads off benchmark yields, interest rates and U.S. Treasury or swap curves and other pricing models utilizing observable inputs and are considered Level 2 investments. Specifically for asset-backed securities, key inputs include prepayment and default projections based on past performance of the underlying collateral and current market data. The following table sets forth, by level within the fair value hierarchy, a summary of the PBOP trust investments measured at fair value on a recurring basis at December 31, 2021 (in millions): PBOP Trust Assets Level 1 Level 2 Level 3 Total Short-term investments $ 4.3 $ — $ — $ 4.3 Fixed income mutual funds 19.2 — — 19.2 Asset-backed securities — 6.9 — 6.9 Corporate bonds — 31.0 — 31.0 Tax exempt securities — 31.6 — 31.6 Total investments $ 23.5 $ 69.5 $ — $ 93.0 The following table sets forth, by level within the fair value hierarchy, a summary of the PBOP trust investments measured at fair value on a recurring basis at December 31, 2020 (in millions): PBOP Trust Assets Level 1 Level 2 Level 3 Total Short-term investments $ 5.7 $ — $ — $ 5.7 Fixed income mutual funds 19.5 — — 19.5 Asset-backed securities — 14.4 — 14.4 Corporate bonds — 23.7 — 23.7 Tax exempt securities — 32.9 — 32.9 Total investments $ 25.2 $ 71.0 $ — $ 96.2 Investment Strategy Pension Plan: The Company employs a total-return approach using a mix of equities and fixed income securities to maximize the long-term return on plan assets for a prudent level of risk and generate cash flows adequate to meet plan requirements. The intent of this strategy is to minimize plan expenses by generating investment returns that exceed the growth of the plan liabilities over the long run. Risk tolerance is established through careful consideration of the plan liabilities, plan funded status and corporate financial conditions. The target allocation of plan assets is 40% to 60% of the investment portfolio to equity and limited partnerships, with the remainder primarily invested in fixed income securities. The investment portfolio contains a diversified blend of fixed income, equity and short-term securities. Alternative investments, including limited partnerships, have been used to enhance risk adjusted long-term returns while improving portfolio diversification. At December 31, 2021, the pension trust had committed approximately $2.0 million to future capital calls from various third party limited partnership investments in exchange for an ownership interest in the related partnerships. Investment risk is monitored through annual liability measurements, periodic asset and liability studies and quarterly investment portfolio reviews. PBOP: The investment strategy for the PBOP assets is to reduce the volatility of plan investments while protecting the initial investment given the overfunded status of the plan. At December 31, 2021 and 2020, all of the PBOP investments were in fixed income securities. Defined Contribution Plan Texas Gas employees hired on or after November 1, 2006, and all other employees of the Company are provided retirement benefits under a defined contribution plan, which also provides 401(k) plan benefits to its participants. Costs related to the Company's defined contribution plan were $12.8 million, $11.9 million and $11.5 million for the years ended December 31, 2021, 2020 and 2019. Long-Term Incentive Compensation Plans The Company grants to selected employees long-term compensation awards under the 2018 LTIP, the LTIP (prior to 2019) and the UAR and Cash Bonus Plan (prior to 2019). These awards are intended to align the interests of the employees with those of the Company, encourage superior performance, attract and retain employees who are essential for the Company's growth and profitability and to encourage employees to devote their best efforts to advancing the Company's business over both long and short-term time horizons. 2018 LTIP The 2018 LTIP provides for grants of Performance Awards to selected employees of the Company. A Performance Award is a long-term incentive award with a stated target amount which is payable in cash, after adjustments, upon vesting based on certain specified performance criteria being met. The stated target can be adjusted based on the level of achievement of the performance goals for the vesting period, but not to be below 90% or to exceed 110% of the target amount. In the case of retirement, any outstanding and unvested awards would become fully vested upon retirement and the Performance Awards will be paid at the original vesting date. In 2021 and 2020, the Company granted to certain employees $12.4 million and $12.2 million of Performance Awards. The Company recorded compensation expense of $12.7 million, $10.9 million and $6.1 million for the years ended December 31, 2021, 2020 and 2019, and had $7.0 million of remaining unrecognized compensation expense related to the Performance Awards as of December 31, 2021 and 2020. LTIP and UAR and Cash Bonus Plan The Company recorded $1.4 million and $6.2 million in Administrative and general expenses during 2020 and 2019 related to the LTIP and the UAR and Cash Bonus Plan.

Income Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company is not a taxable entity for federal income tax purposes. The following is a summary of the provision for income taxes for the years ended December 31, 2021, 2020 and 2019 (in millions): For the Year Ended December 31, 2021 2020 2019 Current expense: State $ 0.5 $ 0.1 $ 0.4 Deferred provision: State 0.2 0.2 0.1 Income taxes $ 0.7 $ 0.3 $ 0.5 The Company's tax years 2018 through 2021 remain subject to examination by the Internal Revenue Service and the states in which it operates. There were no differences between the provision at the statutory rate to the income tax provision at December 31, 2021, 2020 and 2019. As of December 31, 2021 and 2020, there were no significant deferred income tax assets or liabilities.

Credit Risk

Credit Risk	12 Months Ended
Credit Risk	Dec. 31, 2021
Risks and Uncertainties [Abstract]
Credit Risk	Credit Risk Major Customers For the years ended December 31, 2021 and 2019, no customer comprised 10% or more of the Company's operating revenues. For the year ended December 31, 2020, the Company earned $132.5 million of operating revenues from one customer which represented approximately 10% of total operating revenues. Gas Loaned to Customers Natural gas price volatility can cause changes in credit risk related to gas and NGLs loaned to customers. As of December 31, 2021, the amount of gas owed to the Company's operating subsidiaries due to gas imbalances and gas loaned

Related Party Transactions

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2021
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Loews provides a variety of corporate services to the Company under services agreements, including information technology, tax, risk management, internal audit and corporate development services and charges the Company for allocated overheads. The Company incurred charges related to these services of $5.5 million, $5.7 million and $5.7 million for the years ended December 31, 2021, 2020 and 2019, which were recorded in Administrative and general on the Consolidated Statements of Income. Total distributions paid to BPHC and Boardwalk GP were $102.2 million for each of the years ended December 31, 2021, 2020 and 2019.

Accounting Policies (Policies)

Accounting Policies (Policies)	12 Months Ended
Accounting Policies (Policies)	Dec. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP).
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the Company's accounts and those of its wholly owned subsidiaries after elimination of intercompany transactions.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses and disclosure of contingent assets and liabilities and the fair values of certain items. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, which form the basis for making judgments about the carrying amounts of assets and liabilities that are not readily apparent from other sources. Actual results could differ from such estimates.
Segment Information	Segment Information The Company operates in one reportable segment - the operation of interstate natural gas and NGLs pipeline systems and integrated storage facilities. This segment consists of interstate natural gas pipeline systems located in the Gulf Coast region, Oklahoma, Arkansas, Tennessee, Kentucky, Illinois, Indiana and Ohio and integrated natural gas storage facilities located in Indiana, Kentucky, Louisiana and Mississippi, and NGLs pipelines and storage facilities located in Louisiana and Texas.
Regulatory Accounting	Regulatory Accounting Most of the Company's natural gas pipeline subsidiaries are regulated by the Federal Energy Regulatory Commission (FERC). When certain criteria are met, GAAP requires that certain rate-regulated entities account for and report assets and liabilities consistent with the economic effect of the manner in which independent third-party regulators establish rates (regulatory accounting). This basis of accounting is applicable to operations of the Company's Texas Gas subsidiary, which records certain costs and benefits as regulatory assets and liabilities in order to provide for recovery from or refunds to customers in future periods, but is not applicable to the operations associated with the Fayetteville and Greenville Laterals due to rates charged under negotiated rate agreements and a portion of Texas Gas' storage capacity due to the regulatory treatment associated with the rates charged for that capacity. The Company applies regulatory accounting for its fuel trackers on Gulf South, under which the value of fuel received from customers paying the maximum tariff rate and the related value of fuel used in transportation are recorded to a regulatory asset or liability depending on whether Gulf South uses more fuel than it collects from customers or collects more fuel than it uses. Other than as described for Texas Gas and for the fuel trackers on Gulf South, regulatory accounting is not applicable to the Company's other FERC-regulated operations. The Company monitors the regulatory and competitive environment in which it operates to determine whether its regulatory assets continue to be probable of recovery. If the Company determines that all or a portion of its regulatory assets no longer meets the criteria for recognition as regulatory assets, that portion which is not recoverable will be written off, net of any regulatory liabilities. Note 10 contains more information regarding the Company's regulatory assets and liabilities.
Fair Value Measurements	Fair Value Measurements Fair value refers to an exit price that would be received to sell an asset or paid to transfer a liability in an orderly transaction in the principal market in which the reporting entity transacts based on the assumptions market participants would use when pricing the asset or liability assuming its highest and best use. A fair value hierarchy has been established that prioritizes the information used to develop those assumptions giving priority, from highest to lowest, to quoted prices in active markets for identical assets and liabilities (Level 1); observable inputs not included in Level 1, for example, quoted prices for similar assets and liabilities (Level 2); and unobservable data (Level 3), for example, a reporting entity's own internal data based on the best information available in the circumstances. The Company uses fair value measurements to account for asset retirement obligations (ARO) and any impairment charges. Notes 6 and 12 contain more information regarding fair value measurements.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash equivalents are highly liquid investments with an original maturity of three months or less and are stated at cost plus accrued interest, which approximates fair value. The Company had no restricted cash at December 31, 2021 and 2020.
Cash Management	Cash Management The operating subsidiaries participate in an intercompany cash management program, with those that are FERC-regulated participating to the extent they are permitted under FERC regulations. Under the cash management program, depending on whether a participating subsidiary has short-term cash surpluses or cash requirements, Boardwalk Pipelines either provides cash to them or they provide cash to Boardwalk Pipelines. The transactions are represented by demand notes and are stated at historical carrying amounts. Interest income and expense are recognized on an accrual basis when collection is reasonably assured. The interest rate on intercompany demand notes is London Interbank Offered Rate (LIBOR), or such benchmark replacement rate, plus 1.00% and is adjusted every three months.
Trade and Other Receivables	Trade and Other Receivables Trade and other receivables are stated at their historical carrying amount, net of allowances for doubtful accounts. The Company establishes an allowance for doubtful accounts under an expected credit loss model based on historical credit loss experience and specific facts and circumstances. Uncollectible receivables are written off when a settlement is reached for an amount that is less than the outstanding historical balance or a receivable amount is deemed otherwise unrealizable.
Gas Stored Underground and Gas Receivables and Payables	Gas Stored Underground and Gas Receivables and Payables Certain of the Company's operating subsidiaries have underground gas in storage which is utilized for system management and operational balancing, as well as for services including firm and interruptible storage associated with certain no-notice and parking and lending (PAL) services. Gas stored underground includes the historical cost of natural gas volumes owned by the operating subsidiaries, at times reduced by certain operational encroachments upon that gas. The operating subsidiaries provide storage services whereby they store natural gas or NGLs on behalf of customers and also periodically hold customer gas under PAL services. Since the customers retain title to the gas held by the Company in providing these services, the Company does not record the related gas on its Consolidated Balance Sheets . Certain of the Company's operating subsidiaries also periodically lend gas and NGLs to customers. In the course of providing transportation and storage services to customers, the operating subsidiaries may receive different quantities of gas from shippers and operators than the quantities delivered on behalf of those shippers and operators. This results in transportation and exchange gas receivables and payables, commonly known as imbalances, which are primarily settled in cash or the receipt or delivery of gas in the future. Settlement of imbalances requires agreement between the pipelines and shippers or operators as to allocations of volumes to specific transportation contracts and timing of delivery of gas based on operational conditions. The receivables and payables are valued at market price for operations where regulatory accounting is not applicable and are valued at the historical value of gas in storage for operations where regulatory accounting is applicable.
Materials and Supplies	Materials and Supplies Materials and supplies are carried at average cost and are included in Other Assets on the Consolidated Balance Sheets. The Company expects its materials and supplies to be used for projects related to its property, plant and equipment (PPE) and for future growth projects. At December 31, 2021 and 2020, the Company held approximately $28.5 million and $25.5 million of materials and supplies.
Property, Plant and Equipment and Repair and Maintenance Costs	Property, Plant and Equipment and Repair and Maintenance Costs PPE is recorded at its original cost of construction or fair value of assets purchased. Construction costs and expenditures for major renewals and improvements which extend the lives of the respective assets are capitalized. Construction work in progress is included in the financial statements as a component of PPE. Repair and maintenance costs are expensed as incurred. Depreciation of PPE related to operations for which regulatory accounting does not apply is provided for using the straight-line method of depreciation over the estimated useful lives of the assets, which range from 3 to 35 years. The ordinary sale or retirement of PPE for these assets could result in a gain or loss being recorded in the income statement. Depreciation of PPE related to operations for which regulatory accounting is applicable is provided for primarily on the straight-line method at FERC-prescribed rates over estimated useful lives of 5 to 62 years. Reflecting the application of composite depreciation, gains and losses from the ordinary sale or retirement of PPE for these assets are not recognized in earnings and generally do not impact PPE, net. Note 7 contains more information regarding the Company's PPE.
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill represents the excess of the cost of an acquisition over the fair value of the net identifiable assets acquired and liabilities assumed. Goodwill is tested for impairment at the reporting unit level at least annually, as of November 30, or more frequently when events occur and circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying amount. A reporting entity may perform an optional qualitative assessment on an annual basis to determine whether events occurred or circumstances changed that would more likely than not reduce the fair value of a reporting unit below its carrying amount. If an initial qualitative assessment identifies that it is more likely than not that the fair value of a reporting unit is less than its carrying amount, or the optional qualitative assessment is not performed, a quantitative analysis is performed. The quantitative goodwill impairment test is performed by calculating the fair value of the reporting unit and comparing it to the reporting unit's carrying amount. If the fair value of a reporting unit exceeds its carrying amount, goodwill of the reporting unit is not impaired. However, if the carrying amount of a reporting unit exceeds its fair value, an impairment loss is recognized in an amount equal to that excess, limited to the total amount of goodwill recorded on the reporting unit. Intangible assets are those assets which provide future economic benefit but have no physical substance. The Company recorded intangible assets for customer relationships obtained through its acquisitions. The customer relationships, which are included in Other Assets on the Consolidated Balance Sheets, have a finite life and are being amortized over their estimated useful lives. Note 8 contains more information regarding the Company's goodwill and intangible assets.
Impairment of Long-Lived Assets (including Tangible and Definite-lived Intangible Assets)	Impairment of Long-lived Assets (including Tangible and Definite-lived Intangible Assets) The Company evaluates its long-lived and intangible assets for impairment when, in management's judgment, events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. When such a determination has been made, management's estimate of undiscounted future cash flows attributable to the remaining economic useful life of the asset (or asset group) is compared to the carrying amount of the asset (or asset group) to determine whether an impairment has occurred. If an impairment of the carrying amount has occurred, the amount of impairment recognized in the financial statements is determined by estimating the fair value of the assets (or asset group) and recording a loss to the extent that the carrying amount exceeds the estimated fair value.
Capitalized Interest and Allowance for Funds Used During Construction (AFUDC)	Capitalized Interest and Allowance for Funds Used During Construction (AFUDC) The Company records capitalized interest, which represents the cost of borrowed funds used to finance construction activities for operations where regulatory accounting is not applicable. The Company records AFUDC, which represents the cost of funds, including equity funds, applicable to regulated natural gas transmission plant under construction as permitted by FERC regulatory practices, in connection with the Company's operations where regulatory accounting is applicable. Capitalized interest and the allowance for borrowed funds used during construction are recognized as a reduction to Interest expense and the allowance for equity funds used during construction is included in Miscellaneous other income, net within the Consolidated Statements of Income. The following table summarizes capitalized interest and the allowance for borrowed funds and allowance for equity funds used during construction (in millions): For the Year Ended 2021 2020 2019 Capitalized interest and allowance for borrowed funds used during construction $ 3.8 $ 6.1 $ 5.6 Allowance for equity funds used during construction 7.9 4.1 1.5
Income Taxes	Income Taxes The Company is not a taxable entity for federal income tax purposes. As such, it does not directly pay federal income tax. The Company's taxable income or loss, which may vary substantially from the net income or loss reported in the Consolidated Statements of Income, is includable in the federal income tax returns of each of its partners. The aggregate difference in the basis of the Company's net assets for financial and income tax purposes is $4.7 billion. The subsidiaries of the Company directly incur some income-based state taxes which are presented in Income taxes on the Consolidated Statements of Income. Note 13 contains more information regarding the Company's income taxes.
Asset Retirement Obligations	Asset Retirement Obligations The accounting requirements for existing legal obligations associated with the future retirement of long-lived assets require entities to record the fair value of a liability for an ARO in the period during which the liability is incurred. The liability is initially recognized at fair value and is increased with the passage of time as accretion expense is recorded, until the liability is ultimately settled. The accretion expense is included within Operation and maintenance costs within the Consolidated Statements of Income. An amount corresponding to the amount of the initial liability is capitalized as part of the carrying amount of the related long-lived asset and depreciated over the useful life of that asset. Note 9 contains more information regarding the Company's ARO.
Environmental Liabilities	Environmental Liabilities The Company records environmental liabilities based on management's estimates of the undiscounted future obligation for probable costs associated with environmental assessment and remediation of operating sites. These estimates are based on evaluations and discussions with counsel and operating personnel and the current known facts and circumstances related to these environmental matters. Note 5 contains more information regarding the Company's environmental liabilities.
Defined Benefit Plans	Defined Benefit Plans The Company maintains postretirement benefit plans for certain employees. The Company funds these plans through periodic contributions which are invested until the benefits are paid out to the participants, and records an asset or liability based on the overfunded or underfunded status of the plan. The net benefit costs of the plans are recorded in the Consolidated Statements of Income. Any deferred amounts related to unrecognized gains and losses or changes in actuarial assumptions are recorded as either a regulatory asset or liability or recorded as a component of accumulated other comprehensive income (AOCI) until those gains or losses are recognized in the Consolidated Statements of Income. Note 12 contains more information regarding the Company's pension and postretirement benefit obligations.
Long-Term Compensation	Long-Term Compensation The Company provides performance awards (Performance Awards) to certain of its employees under its 2018 Long-Term Incentive Plan (2018 LTIP). A Performance Award is a long-term incentive award with a stated target amount which is payable in cash, after certain adjustments, upon vesting based on certain specified performance criteria being met. Prior to 2019, the Company provided awards of phantom common units (Phantom Common Units) to certain employees under its Long-Term Incentive Plan (LTIP) and awards of long-term cash bonuses (Long-Term Cash Bonuses) under the Boardwalk Pipeline Partners Unit Appreciation Rights (UAR) and Cash Bonus Plan. Since 2018, the Company has not granted awards in the form of Phantom Common Units or as Long-Term Cash Bonuses and as of December 31, 2020, all Phantom Common Units and Long-Term Cash Bonuses had vested and were paid. The Company measures the cost of an award issued in exchange for employee services based on the stated target amount for Performance Awards. All outstanding awards are required to be settled in cash and are classified as a liability until settlement. The related compensation expense, less forfeitures, is recognized over the period that employees are required to provide services in exchange for the awards, usually the vesting period. Note 12 contains more information regarding the Company's long-term compensation.
Partner Capital Accounts	Partner Capital Accounts For purposes of maintaining capital accounts, items of income and loss of the Company are allocated among the partners each period, or portion thereof, in accordance with the partnership agreement, based on their respective ownership interests.
Leases	Leases Operating lease right-of-use assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. The discount rate used to determine the commencement date present value of lease payments is typically the Company's secured borrowing rate, as the implicit rate of most of the Company's leases is not readily determinable. The Company has elected not to record any leases with terms of twelve months or less on the Consolidated Balance Sheets.
Revenue Recognition	Revenue Recognition Nature of Contracts The Company primarily earns revenues from contracts with customers by providing transportation and storage services for natural gas and NGLs on a firm and interruptible basis. The Company also provides interruptible natural gas PAL services. The Company's customers choose, based upon their particular needs, the applicable mix of services depending upon availability of pipeline and storage capacity, the price of services and the volume and timing of customer requirements. The maximum rates that may be charged by the majority of the Company's operating subsidiaries are established through the FERC's cost-based rate-making process; however, rates actually charged by those operating subsidiaries may be less than those allowed by the FERC. Under the FERC regulations, certain revenues that the Company's subsidiaries collect may be subject to possible refunds to customers. Accordingly, during a rate case, estimated refund liabilities are recorded considering regulatory proceedings, advice of counsel and estimated risk-adjusted total exposure, as well as other factors. The Company's service contracts can range from one twenty ten thirty Firm Service Contracts : The Company offers firm services to its customers. The Company's customers can reserve a specific amount of pipeline capacity at specified receipt and delivery points on the Company's pipeline system (transportation service) or can reserve a specific amount of storage capacity at specified injection and withdrawal points at the Company's storage facilities (storage service). The Company accounts for firm services as a single promise to stand ready each month of the contract term to provide the committed capacity for either transportation or storage services when needed by the customer, which represents a series of distinct monthly services that are substantially the same with the same pattern of transfer to the customer. Although several activities may be required to provide the firm service, the individual activities do not represent distinct performance obligations because all of the activities must be performed in combination in order for the Company to provide the firm service. The transaction price for firm service contracts is comprised of a fixed fee based on the quantity of capacity reserved, regardless of use (capacity reservation fee), plus variable fees in the form of a usage fee paid on the volume of commodity actually transported or injected and withdrawn from storage. Both the fixed and usage fees are allocated to the single performance obligation of providing transportation or storage service and recognized over time based upon the output measure of time as the Company completes its stand-ready obligation to provide contracted capacity and the customer receives and consumes the benefit of the reserved capacity, which corresponds with the transfer of control to the customer. The fixed fee is recognized ratably over the contract term, representative of the proportion of the committed stand-ready capacity obligation that has been fulfilled to date, and the usage fee is recognized upon satisfaction of each distinct monthly performance obligation, consistent with the allocation objective and based upon the level of effort required to satisfy the stand-ready obligation in a given month. Capacity reservation revenues derived from a firm service contract are generally consistent during the contract term, but can be higher in winter periods than the rest of the year based upon seasonal rates. Interruptible Service Contracts : In providing interruptible services to customers, the Company agrees to transport or store natural gas or NGLs for a customer when capacity is available. The Company does not account for interruptible services with a customer as a contract until the customer nominates for service and the Company accepts the nomination based upon available pipeline or storage capacity because there are no enforceable rights and obligations until that time. The nomination and acceptance process is a daily activity and acceptance is granted based upon priority of service and availability of capacity. Upon acceptance, the Company accounts for interruptible services similarly to its firm services. The transaction price for interruptible service contracts is comprised of a variable fee in the form of a usage fee paid on the volume of commodity actually transported or injected and withdrawn from storage. The usage fee is allocated to the single performance obligation of providing interruptible service. Interruptible service revenues are generally recognized over time based on the output measure of volume transported or stored when services are rendered upon the successful allocation of the services provided to the customer's account, which best depicts the transfer of control to the customer and satisfaction of the promised service. Interruptible services are recognized in the month services are provided because the Company has a right to consideration from customers in amounts that correspond directly to the value that the customer receives from the Company's performance. The rates charged may vary on a daily, monthly or seasonal basis. Minimum Volume Commitment (MVC) Contracts : Certain of the Company's transportation or storage contracts require customers to transport or store a minimum volume of commodity over a specified time period. If a customer fails to meet its MVC for the specified time period, the customer is obligated to pay a contractually-determined deficiency fee based upon the shortfall between the actual volumes transported or stored and the MVC for that period. MVC contracts are similar in nature to a firm service contract where the performance obligation is a stand-ready obligation that is a series of distinct services that are substantially the same with the same pattern of transfer to the customer. The transaction price for an MVC is a fee for the volume of commodity actually transported or stored, which is allocated to each distinct monthly performance obligation, consistent with the allocation objective and based upon the level of effort required to satisfy the obligation of the transacted service in a given month. Revenues are generally recognized over time based on the output measure of volume transported or stored, with the recognition of the deficiency fee in the period when it is known the customer cannot make up the deficient volume in the specified period. Other : Periodically, the Company may enter into contracts with customers for the sale of natural gas or NGLs. The Company recognizes revenues for these transactions at the point in time of the physical sale of the commodity, which corresponds with the transfer of control of the commodity to the customer and the consideration is measured as the stated sales price in the contract. Contract Balances The Company records contract assets primarily related to performance obligations completed but not billed, or partially billed, as of the reporting date. The Company records contract liabilities, or deferred income, when payment is received in advance of satisfying its performance obligations.

Accounting Policies (Tables)

Accounting Policies (Tables)	12 Months Ended
Accounting Policies (Tables)	Dec. 31, 2021
Accounting Policies [Abstract]
Summary of Capitalized Interest and Allowance for Borrowed Funds	The following table summarizes capitalized interest and the allowance for borrowed funds and allowance for equity funds used during construction (in millions): For the Year Ended 2021 2020 2019 Capitalized interest and allowance for borrowed funds used during construction $ 3.8 $ 6.1 $ 5.6 Allowance for equity funds used during construction 7.9 4.1 1.5

Revenues (Tables)

Revenues (Tables)	12 Months Ended
Revenues (Tables)	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following table presents the Company's revenues disaggregated by type of service for the years ended December 31, 2021, 2020 and 2019 (in millions): For the Year Ended December 31, 2021 2020 2019 Revenues from Contracts with Customers Firm Service (1) $ 1,247.5 $ 1,211.7 $ 1,228.3 Interruptible Service 32.0 33.2 29.0 Other revenues 26.1 18.9 9.1 Total Revenues from Contracts with Customers 1,305.6 1,263.8 1,266.4 Other operating revenues (2) 34.5 33.8 28.8 Total Operating Revenues $ 1,340.1 $ 1,297.6 $ 1,295.2 (1) Revenues earned from contracts with MVCs are included in firm service given the stand-ready nature of the performance obligation and the guaranteed nature of the fees over the contract term. The years ended December 31, 2020 and 2019, contain $34.4 million and $26.2 million of incremental revenues received related to customer bankruptcies as discussed in Note 5. (2) Other operating revenues include certain revenues earned from operating leases, pipeline management fees and other activities that are not considered central and ongoing major business operations of the Company and do not represent revenues earned from contracts with customers.
Contract Liabilities	Significant changes in the contract liability balances during the year ended December 31, 2021, are as follows (in millions): Contract Liabilities Balance as of December 31, 2020 (1) $ 17.2 Revenues recognized that were included in the contract liability (5.3) Increases due to cash received, excluding amounts recognized as 7.3 Balance as of December 31, 2021 (1) $ 19.2 (1) As of December 31, 2021 and 2020, $3.6 million a nd $4.9 million were recorded in Other current liabilities (current portion) and $15.6 million and $12.3 million were recorded in Other Liabilities (noncurrent portion). Significant changes in the contract liability balances during the year ended December 31, 2020, are as follows (in millions): Contract Liabilities Balance as of December 31, 2019 (1) $ 11.8 Revenues recognized that were included in the contract liability (5.1) Increases due to cash received, excluding amounts recognized as 10.5 Balance as of December 31, 2020 (1) $ 17.2 (1) As of December 31, 2020 and 2019, $4.9 million and $2.2 million were recorded in Other current liabilities (current portion) and $12.3 million and $9.6 million were recorded in Other Liabilities (noncurrent portion).
Remaining Performance Obligation	The following table includes estimated operating revenues expected to be recognized in the future related to agreements that contain performance obligations that were unsatisfied as of December 31, 2021. The amounts presented primarily consist of fixed fees or MVCs which are typically recognized over time as the performance obligation is satisfied, in accordance with firm service contracts. The Company's customers that are charged maximum tariff rates related to its FERC-regulated operating subsidiaries, the amounts below reflect the current tariff rate for such services for the term of the agreements; however, the tariff rates may be subject to future adjustment. The Company has elected to exclude the following from the table: (a) unsatisfied performance obligations from usage fees associated with its firm services because of the stand-ready nature of such services; (b) consideration in contracts that is recognized in revenue as invoiced, such as for interruptible services; and (c) consideration received prior to December 31, 2021, that will be recognized in revenue in future periods, such as the consideration recorded in contract liabilities. The estimated revenues reflected in the table may include estimated revenues that are anticipated under executed precedent transportation agreements for projects that are subject to regulatory approvals. In millions 2022 2023 Thereafter Total Estimated revenues from contracts with customers from unsatisfied performance obligations as of December 31, 2021 $ 1,115.0 $ 1,015.0 $ 6,704.5 $ 8,834.5 Operating revenues which are fixed and 25.0 25.0 175.5 225.5 Total projected operating revenues under committed firm agreements as of December 31, 2021 $ 1,140.0 $ 1,040.0 $ 6,880.0 $ 9,060.0

Leases (Tables)

Leases (Tables)	12 Months Ended
Leases (Tables)	Dec. 31, 2021
Leases [Abstract]
Components of Lease Cost	The components of lease cost were as follows (in millions): For the Year Ended December 31, 2021 2020 2019 Operating lease cost $ 4.0 $ 4.2 $ 4.3 Short-term lease cost 2.9 3.9 2.6 Finance lease cost: Amortization of right-of-use asset 0.7 0.7 0.7 Interest on lease liability 0.4 0.4 0.5 Total lease cost $ 8.0 $ 9.2 $ 8.1
Schedule of Supplemental Balance Sheet Information Related to Leases	The following provides supplemental balance sheet information related to the Company's leases: As of December 31, 2021 2020 Right-of-use assets (in millions) Operating leases (recorded in Other Assets ) $ 21.6 $ 11.8 Finance lease (recorded in Property, Plant and Equipment ) 4.7 5.4 Lease liabilities (in millions) Operating leases (recorded in Other Liabilities , current and non-current) 23.5 13.8 Finance lease 6.1 6.8 Weighted-average remaining lease term (years) Operating leases 10.8 3.8 Finance lease 6.6 7.6 Weighted-average discount rate Operating leases 2.94 % 4.72 % Finance lease 5.89 % 5.89 %
Maturity of Operating Lease Liabilities	The table below presents the maturities of lease liabilities (in millions): As of December 31, 2021 Operating Finance 2022 $ 3.7 $ 1.1 2023 3.8 1.1 2024 2.5 1.1 2025 2.2 1.1 2026 1.5 1.1 Thereafter 13.6 1.8 Total 27.3 7.3 Less: discount (3.8) (1.2) Total lease liabilities $ 23.5 $ 6.1
Maturity of Finance Lease Liabilities	The table below presents the maturities of lease liabilities (in millions): As of December 31, 2021 Operating Finance 2022 $ 3.7 $ 1.1 2023 3.8 1.1 2024 2.5 1.1 2025 2.2 1.1 2026 1.5 1.1 Thereafter 13.6 1.8 Total 27.3 7.3 Less: discount (3.8) (1.2) Total lease liabilities $ 23.5 $ 6.1

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
Fair Value Measurements (Tables)	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value, by Balance Sheet Grouping	The carrying amounts and estimated fair values of the Company's financial assets and liabilities which were not recorded at fair value on the Consolidated Balance Sheets as of December 31, 2021 and 2020, were as follows (in millions): As of December 31, 2021 Estimated Fair Value Financial Assets Carrying Amount Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 39.1 $ 39.1 $ — $ — $ 39.1 Financial Liabilities Long-term debt $ 3,334.0 (1) $ — $ 3,631.5 $ — $ 3,631.5 (1) The carrying amount of long-term debt excludes a $5.3 million long-term finance lease obligation and $4.8 million of unamortized debt issuance costs. As of December 31, 2020 Estimated Fair Value Financial Assets Carrying Amount Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 2.9 $ 2.9 $ — $ — $ 2.9 Financial Liabilities Long-term debt $ 3,460.4 (1) $ — $ 3,847.6 $ — $ 3,847.6 (1) The carrying amount of long-term debt excludes a $6.1 million long-term finance lease obligation and $5.8 million of unamortized debt issuance costs.

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
Property, Plant and Equipment (Tables)	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	The following table presents the Company's PPE as of December 31, 2021 and 2020 (in millions): Category 2021 Weighted-Average 2020 Weighted-Average Depreciable plant: Transmission $ 10,672.7 37 $ 10,417.9 37 Storage 886.5 38 863.5 38 Gathering 109.6 23 108.0 23 General 228.6 15 224.9 14 Rights of way and other 153.7 33 153.2 33 Total utility depreciable plant 12,051.1 37 11,767.5 37 Non-depreciable: Construction work in progress 239.5 184.2 Storage 152.3 152.3 Land 45.2 44.3 Total non-depreciable assets 437.0 380.8 Total PPE 12,488.1 12,148.3 Less: accumulated depreciation 3,947.0 3,598.5 Total PPE, net $ 8,541.1 $ 8,549.8
Gross PPE Investments and Related Accumulated Depreciation	The following table presents the gross PPE investment and related accumulated depreciation for the Company's undivided interests as of December 31, 2021 and 2020 (in millions): 2021 2020 Gross PPE Accumulated Depreciation Gross PPE Accumulated Depreciation Mobile Bay Pipeline $ 14.6 $ 7.5 $ 14.5 $ 7.1 NGLs pipelines and facilities 51.3 10.4 42.5 8.8 Offshore and other assets 12.8 10.4 12.8 10.1 Total $ 78.7 $ 28.3 $ 69.8 $ 26.0

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
Goodwill and Intangible Assets (Tables)	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The following table contains information regarding the Company's intangible assets, which includes customer relationships acquired as part of its acquisitions (in millions): As of December 31, 2021 2020 Gross carrying amount $ 59.4 $ 59.4 Accumulated amortization (17.2) (15.3) Net carrying amount $ 42.2 $ 44.1
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Amortization expense for the next five years and in total thereafter as of December 31, 2021, is expected to be as follows (in millions): 2022 $ 1.9 2023 1.9 2024 2.0 2025 2.0 2026 2.0 Thereafter 32.4 Total $ 42.2

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
Asset Retirement Obligations (Tables)	Dec. 31, 2021
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligation	The following table summarizes the aggregate carrying amount of the Company's ARO as of December 31, 2021 and 2020 (in millions): 2021 2020 Balance at beginning of year $ 63.1 $ 60.4 Liabilities recorded 9.5 1.3 Liabilities settled (2.2) (0.9) Accretion expense 2.9 2.3 Revision of estimates (8.4) — Balance at end of year 64.9 63.1 Less: Current portion of ARO (3.4) (8.2) Long-term ARO $ 61.5 $ 54.9

Regulatory Assets and Liabili_2

Regulatory Assets and Liabilities (Tables)	12 Months Ended
Regulatory Assets and Liabilities (Tables)	Dec. 31, 2021
Regulatory Assets and Liabilities Disclosure [Abstract]
Schedule of Regulatory Assets	The amounts recorded as regulatory assets and liabilities on the Consolidated Balance Sheets as of December 31, 2021 and 2020, are summarized in the table below. The table also includes amounts related to unamortized debt issuance costs and unamortized discount on long-term debt, which while not regulatory assets and liabilities, are a critical component of the embedded cost of debt financing utilized in Texas Gas' rate proceedings. The tax effect of the equity component of AFUDC represents amounts recoverable from rate payers for the tax recorded in regulatory accounting. Certain amounts in the table are reflected as a negative, or a reduction, to be consistent with the regulatory books of account. The period of recovery for the regulatory assets included in rates varies from one eighteen yet included in rates would be determined in future rate proceedings. None of the regulatory assets shown below were earning a return as of December 31, 2021 and 2020 (in millions): 2021 2020 Regulatory Assets: Pension $ 8.1 $ 10.6 Tax effect of AFUDC equity 0.4 0.6 Fuel tracker 6.8 4.2 Other 0.5 0.5 Total regulatory assets $ 15.8 $ 15.9
Schedule of Regulatory Liabilities	Regulatory Liabilities: Cashout and fuel tracker $ 12.7 $ 14.1 Provision for other asset retirement 88.2 81.6 Unamortized debt issuance costs (1.5) (1.8) Unamortized discount on long-term debt (0.2) (0.2) Postretirement benefits other than pension 64.7 63.3 Total regulatory liabilities $ 163.9 $ 157.0

Financing (Tables)

Financing (Tables)	12 Months Ended
Financing (Tables)	Dec. 31, 2021
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	The following table presents all long-term debt issuances outstanding as of December 31, 2021 and 2020 (in millions): 2021 2020 Notes and Debentures: Boardwalk Pipelines 3.375% Notes due 2023 $ 300.0 $ 300.0 4.95% Notes due 2024 600.0 600.0 5.95% Notes due 2026 550.0 550.0 4.45% Notes due 2027 500.0 500.0 4.80% Notes due 2029 500.0 500.0 3.40% Notes due 2031 500.0 500.0 Gulf South 4.00% Notes due 2022 (Gulf South Notes) 300.0 300.0 Texas Gas 7.25% Debentures due 2027 100.0 100.0 Total notes and debentures 3,350.0 3,350.0 Revolving Credit Facility: Gulf South — 30.0 Texas Gas — 100.0 Total revolving credit facility — 130.0 Finance lease obligation 5.3 6.1 3,355.3 3,486.1 Less: Unamortized debt discount (16.0) (19.6) Unamortized debt issuance costs (4.8) (5.8) Total Long-Term Debt and Finance Lease Obligation $ 3,334.5 $ 3,460.7 no new debt issuances for the year ended December 31, 2021. For the years ended December 31, 2020 and 2019, the Company completed the following debt issuances (in millions, except interest rates): Date of Issuing Subsidiary Amount of Purchaser Net Interest Maturity Date Interest August 2020 Boardwalk Pipelines $ 500.0 $ 5.0 $ 495.0 (1) 3.40 % February 15, 2031 February 15 and August 15 May 2019 Boardwalk Pipelines $ 500.0 $ 4.8 $ 495.2 (2) 4.80 % May 3, 2029 May 3 and November 3 (1) The net proceeds of this offering were used to retire the outstanding $440.0 million aggregate principal amount of Texas Gas 4.50% notes due 2021 on November 3, 2020, to fund growth capital expenditures and for general partnership purposes. (2) The net proceeds of this offering were used to retire the outstanding $350.0 million aggregate principal amount of Boardwalk Pipelines 5.75% notes due 2019 at maturity and for general partnership purposes.
Schedule of Maturities of Long-term Debt	Maturities of the Company's long-term debt for the next five years and in total thereafter are as follows (in millions): 2022 $ 300.0 2023 300.0 2024 600.0 2025 — 2026 550.0 Thereafter 1,600.0 Total long-term debt $ 3,350.0

Employee Benefits (Tables)

Employee Benefits (Tables)	12 Months Ended
Employee Benefits (Tables)	Dec. 31, 2021
Retirement Benefits [Abstract]
Projected Benefit Obligation, Fair Value of Assets, Funded Status and the Amounts Not Yet Recognized As Components of Net Periodic Pension and Postretirement Benefits Cost	Projected Benefit Obligation, Fair Value of Assets and Funded Status The projected benefit obligation, fair value of assets, funded status and the amounts not yet recognized as components of net periodic pension and postretirement benefits cost for the Retirement Plans and PBOP at December 31, 2021 and 2020, were as follows (in millions): Retirement Plans PBOP For the Year Ended For the Year Ended 2021 2020 2021 2020 Change in benefit obligation: Benefit obligation at beginning of period $ 120.7 $ 122.2 $ 35.2 $ 36.5 Service cost 2.6 2.8 0.1 0.1 Interest cost 2.1 2.7 0.9 1.1 Plan participants' contributions — — 1.1 1.1 Actuarial (gain) loss (1.4) 6.0 (2.6) (0.3) Benefits paid (0.5) (0.5) (4.1) (3.3) Settlements (14.4) (12.5) — — Benefit obligation at end of period $ 109.1 $ 120.7 $ 30.6 $ 35.2 Change in plan assets: Fair value of plan assets at beginning of period $ 102.7 $ 101.7 $ 96.2 $ 90.8 Actual return on plan assets 10.5 10.4 (0.3) 7.5 Company's contribution 5.2 3.6 0.1 0.1 Plan participants' contributions — — 1.1 1.1 Benefits paid (0.5) (0.5) (4.1) (3.3) Settlements (14.4) (12.5) — — Fair value of plan assets at end of period $ 103.5 $ 102.7 $ 93.0 $ 96.2 Funded status $ (5.6) $ (18.0) $ 62.4 $ 61.0 Items not recognized as components of net periodic cost: Net actuarial loss (gain) $ 10.0 $ 18.2 $ (2.9) $ (3.4)
Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets	At December 31, 2021 and 2020, the following aggregate information relates only to the underfunded plans (in millions): Retirement Plans For the Year Ended 2021 2020 Projected benefit obligation $ 109.1 $ 120.7 Accumulated benefit obligation 103.4 113.7 Fair value of plan assets 103.5 102.7
Schedule of Net Periodic Benefit Cost	Components of Net Periodic Benefit Cost Components of net periodic benefit cost for both the Retirement Plans and PBOP for the years ended December 31, 2021, 2020 and 2019, were as follows (in millions): Retirement Plans PBOP For the Year Ended For the Year Ended 2021 2020 2019 2021 2020 2019 Service cost $ 2.6 $ 2.8 $ 3.0 $ 0.1 $ 0.1 $ 0.1 Interest cost 2.1 2.7 3.9 0.9 1.1 1.4 Expected return on plan assets (6.2) (6.3) (6.4) (2.7) (3.2) (3.0) Amortization of unrecognized net loss 0.8 1.9 2.2 — — — Settlement charge 1.6 2.4 2.9 — — — Regulatory asset decrease 2.5 — — — — — Net periodic benefit cost $ 3.4 $ 3.5 $ 5.6 $ (1.7) $ (2.0) $ (1.5)
Schedule of Expected Benefit Payments	Estimated Future Benefit Payments The following table shows benefit payments, which reflect expected future service, as appropriate, which are expected to be paid for both the Retirement Plans and PBOP (in millions): Retirement Plans PBOP 2022 $ 21.8 $ 2.1 2023 11.9 2.1 2024 10.7 2.0 2025 11.9 1.9 2026 10.1 1.9 2027-2031 34.5 7.5
Weighted-Average Assumptions Used to Determine Benefit Obligations	Weighted-Average Assumptions Weighted-average assumptions used to determine benefit obligations for the years ended December 31, 2021 and 2020, were as follows: Retirement Plans PBOP For the Year Ended For the Year Ended 2021 2020 2021 2020 Pension SRP Pension SRP Discount rate 2.30 % 2.35 % 1.70 % 1.55 % 2.90 % 2.60 % Expected return on plan assets 6.25 % 6.25 % 6.50 % 6.50 % 2.01 % 2.81 % Rate of compensation increase 3.00 % 3.00 % 3.00 % 3.00 % — —
Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost	Weighted-average assumptions used to determine net periodic benefit cost for the periods indicated were as follows: Retirement Plans PBOP For the Year Ended For the Year Ended 2021 2020 2019 2021 2020 2019 Pension SRP Pension SRP Pension SRP Discount rate (1) 1.55 % (1) 2.70 % (1) 4.10 % 2.60 % 3.30 % 4.30 % Expected return on plan assets 6.50% 6.50 % 7.00% 7.00 % 7.00% 7.00 % 2.81 % 3.61 % 3.61 % Rate of compensation increase 3.00% 3.00 % 3.00% 3.00 % 3.86% 3.86 % — — — (1) Pension expense was remeasured quarterly in 2021, 2020 and 2019. The quarterly remeasurements for each quarter in 2021, 2020 and 2019 were as follows: Quarter 1: 2.05%, 2.95% and 3.80%; Quarter 2: 2.05%, 2.20% and 3.25%; Quarter 3: 1.95%, 1.85% and 2.60%; and Quarter 4: 2.30%, 1.70% and 2.70%.
Fair Values of Pension Plan Assets By Asset Class Master Trust	The following table sets forth, by level within the fair value hierarchy, a summary of the Master Trust's investments measured at fair value on a recurring basis at December 31, 2021 (in millions): Master Trust Assets Measured under Fair Value Hierarchy Measured at Net Asset Value Total Master Trust Assets Level 1 Level 2 Level 3 Total Equity securities $ 69.1 $ — $ — $ 69.1 $ — $ 69.1 Short-term investments 1.9 — — 1.9 — 1.9 Other assets 2.2 — — 2.2 — 2.2 Fixed income mutual funds 111.3 — — 111.3 — 111.3 Total assets measured at fair 184.5 — — 184.5 — 184.5 Total limited partnerships — — — — 54.9 54.9 Total $ 184.5 $ — $ — $ 184.5 $ 54.9 $ 239.4 The following table sets forth, by level within the fair value hierarchy, a summary of the Master Trust's investments measured at fair value on a recurring basis at December 31, 2020 (in millions): Master Trust Assets Measured under Fair Value Hierarchy Measured at Net Asset Value Total Master Trust Assets Level 1 Level 2 Level 3 Total Equity securities $ 59.9 $ — $ — $ 59.9 $ — $ 59.9 Short-term investments 3.9 — — 3.9 — 3.9 Fixed income mutual funds 112.5 — — 112.5 — 112.5 Total assets measured at fair 176.3 — — 176.3 — 176.3 Total limited partnerships — — — — 57.5 57.5 Total $ 176.3 $ — $ — $ 176.3 $ 57.5 $ 233.8
Fair Values of PBOP Plan Assets By Asset Class	The following table sets forth, by level within the fair value hierarchy, a summary of the PBOP trust investments measured at fair value on a recurring basis at December 31, 2021 (in millions): PBOP Trust Assets Level 1 Level 2 Level 3 Total Short-term investments $ 4.3 $ — $ — $ 4.3 Fixed income mutual funds 19.2 — — 19.2 Asset-backed securities — 6.9 — 6.9 Corporate bonds — 31.0 — 31.0 Tax exempt securities — 31.6 — 31.6 Total investments $ 23.5 $ 69.5 $ — $ 93.0 The following table sets forth, by level within the fair value hierarchy, a summary of the PBOP trust investments measured at fair value on a recurring basis at December 31, 2020 (in millions): PBOP Trust Assets Level 1 Level 2 Level 3 Total Short-term investments $ 5.7 $ — $ — $ 5.7 Fixed income mutual funds 19.5 — — 19.5 Asset-backed securities — 14.4 — 14.4 Corporate bonds — 23.7 — 23.7 Tax exempt securities — 32.9 — 32.9 Total investments $ 25.2 $ 71.0 $ — $ 96.2

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense	The following is a summary of the provision for income taxes for the years ended December 31, 2021, 2020 and 2019 (in millions): For the Year Ended December 31, 2021 2020 2019 Current expense: State $ 0.5 $ 0.1 $ 0.4 Deferred provision: State 0.2 0.2 0.1 Income taxes $ 0.7 $ 0.3 $ 0.5

Corporate Structure (Details)

Corporate Structure (Details)	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Percent of Company's Capital Directly and Indirectly Owned by Holding Company	100.00%

Accounting Policies (Details)

Accounting Policies (Details) $ in Millions	12 Months Ended
Accounting Policies (Details) $ in Millions	Dec. 31, 2021USD ($)segments	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Accounting Policies [Abstract]
Number of Reportable Segments (in ones) \| segments	1
Restricted Cash and Cash Equivalents	$ 0	$ 0
Materials And Supplies Held In Other Assets	28.5	25.5
Capitalized interest and allowance for borrowed funds used during construction	3.8	6.1	$ 5.6
Allowance for equity funds used during construction	7.9	$ 4.1	$ 1.5
Aggregate basis difference in net assets for financial and income tax purposes	$ 4,700
Minimum
Service Contracts Duration (years)	1 year
Expected Payment of Invoiced Services (days)	10 days
Maximum
Service Contracts Duration (years)	20 years
Expected Payment of Invoiced Services (days)	30 days

Basis of Presentation and Acc_2

Basis of Presentation and Accounting Policies Property, Plant and Equipment (PPE) and Repair and Maintenance Costs (Details)	12 Months Ended
	Dec. 31, 2021
Minimum
Property, Plant and Equipment [Line Items]
Depreciation range for PPE related to operations for which regulatory accounting does not apply	3 years
Depreciation range for PPE related to operations for which regulatory accounting is applicable	5 years
Maximum
Property, Plant and Equipment [Line Items]
Depreciation range for PPE related to operations for which regulatory accounting does not apply	35 years
Depreciation range for PPE related to operations for which regulatory accounting is applicable	62 years

Revenues Disaggregation of Reve

Revenues Disaggregation of Revenue (Details) $ in Millions		12 Months Ended
Revenues Disaggregation of Revenue (Details) $ in Millions		Dec. 31, 2021USD ($)segments	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Disaggregation of Revenue [Abstract]
Number of Reportable Segments (in ones) \| segments		1
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers		$ 1,305.6	$ 1,263.8	$ 1,266.4
Other operating revenues	[1]	34.5	33.8	28.8
Total operating revenues		1,340.1	1,297.6	1,295.2
Letter of Credit Proceeds Recognized into Transportation Revenue			34.4	26.2
Firm Service
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	[2]	1,247.5	1,211.7	1,228.3
Interruptible Service
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers		32	33.2	29
Other revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers		$ 26.1	$ 18.9	$ 9.1

[1]	Other operating revenues include certain revenues earned from operating leases, pipeline management fees and other activities that are not considered central and ongoing major business operations of the Company and do not represent revenues earned from contracts with customers.
[2]	Revenues earned from contracts with MVCs are included in firm service given the stand-ready nature of the performance obligation and the guaranteed nature of the fees over the contract term. The years ended December 31, 2020 and 2019, contain $34.4 million and $26.2 million of incremental revenues received related to customer bankruptcies as discussed in Note 5.

Revenues Contract Balances (Det

Revenues Contract Balances (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Trade Receivables, net		$ 126.2		$ 115.1
Contracts with Customers, Asset, Gross, Noncurrent		2.3		2.9
Contract Liability Beginning Balance	[1]	17.2	[2]	11.8
Revenues recognized that were included in the contract liability balances at the beginning of the period		(5.3)		(5.1)
Increases due to cash received, excluding amounts recognized as revenues during the period		7.3		10.5
Contract Liability Ending Balance	[2]	19.2		17.2	[1]
Contract with Customer, Liability, Current		3.6		4.9		$ 2.2
Contract with Customer, Liability, Noncurrent		$ 15.6		$ 12.3		$ 9.6

[1]	As of December 31, 2020 and 2019, $4.9 million and $2.2 million were recorded in Other current liabilities (current portion) and $12.3 million and $9.6 million were recorded in Other Liabilities (noncurrent portion).
[2]	As of December 31, 2021 and 2020, $3.6 million a nd $4.9 million were recorded in Other current liabilities (current portion) and $15.6 million and $12.3 million were recorded in Other Liabilities (noncurrent portion).

Revenues Performance Obligation

Revenues Performance Obligations (Details) $ in Millions	12 Months Ended
Revenues Performance Obligations (Details) $ in Millions	Dec. 31, 2021USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Estimated revenues from contracts with customers from unsatisfied performance obligations as of December 31, 2021	$ 1,115
Operating revenues which are fixed and determinable (operating leases)	25
Total projected operating revenues under committed firm agreements as of December 31, 2021	$ 1,140
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Estimated revenues from contracts with customers from unsatisfied performance obligations as of December 31, 2021	$ 1,015
Operating revenues which are fixed and determinable (operating leases)	25
Total projected operating revenues under committed firm agreements as of December 31, 2021	$ 1,040
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	20 years
Estimated revenues from contracts with customers from unsatisfied performance obligations as of December 31, 2021	$ 6,704.5
Operating revenues which are fixed and determinable (operating leases)	175.5
Total projected operating revenues under committed firm agreements as of December 31, 2021	6,880
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated revenues from contracts with customers from unsatisfied performance obligations as of December 31, 2021	8,834.5
Operating revenues which are fixed and determinable (operating leases)	225.5
Total projected operating revenues under committed firm agreements as of December 31, 2021	$ 9,060

Leases (Details)

Leases (Details)	12 Months Ended
Leases (Details)	Dec. 31, 2021
Leases [Abstract]
Lessee, Finance Lease, Description	The Company also has a finance lease related to the lease of an office building in Owensboro, Kentucky, entered into in 2013, that has a fifteen-year term with two twenty-year renewal options.
Lessee, Finance Lease, Term of Contract	15 years
Lessee, Finance Lease, Renewal Term	40 years

Leases Lease Cost (Details)

Leases Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
Leases Lease Cost (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease cost	$ 4	$ 4.2	$ 4.3
Short-term lease cost	2.9	3.9	2.6
Finance Lease, Amortization of right-of-use asset	0.7	0.7	0.7
Finance Lease, Interest on lease liability	0.4	0.4	0.5
Total lease cost	$ 8	$ 9.2	$ 8.1

Leases Supplemental Balance She

Leases Supplemental Balance Sheet Information Related to Leases (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Right-of-use assets operating leases	$ 21.6	$ 11.8
Right-of-use assets operating leases, statement of financial position	Other	Other
Right-of-use assets finance lease	$ 4.7	$ 5.4
Right-of-use assets finance lease, statement of financial position	Property, Plant and Equipment, Gross	Property, Plant and Equipment, Gross
Operating lease liabilities	$ 23.5	$ 13.8
Operating lease, liability, current, statement of financial position	Other current liabilities	Other current liabilities
Operating lease, liability, noncurrent, statement of financial position	Other	Other
Finance lease liability	$ 6.1	$ 6.8
Finance lease liability, statement of financial position	Long-term debt and finance lease obligation, Other current liabilities	Long-term debt and finance lease obligation, Other current liabilities
Operating lease, weighted-average remaining lease term (years)	10 years 9 months 18 days	3 years 9 months 18 days
Finance lease, weighted-average remaining lease term (years)	6 years 7 months 6 days	7 years 7 months 6 days
Operating lease, weighted-average discount rate, percent	2.94%	4.72%
Finance lease, weighted-average discount rate, percent	5.89%	5.89%

Leases Maturities of Operating

Leases Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
2022	$ 3.7
2023	3.8
2024	2.5
2025	2.2
2026	1.5
Thereafter	13.6
Total	27.3
Less: discount	(3.8)
Total operating lease liabilities	$ 23.5	$ 13.8

Leases Maturities of Financing

Leases Maturities of Financing Lease Liability (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
2022	$ 1.1
2023	1.1
2024	1.1
2025	1.1
2026	1.1
Thereafter	1.8
Total	7.3
Less: discount	(1.2)
Total finance lease liability	$ 6.1	$ 6.8

Commitments and Contingencies L

Commitments and Contingencies Legal Proceedings (Details) - Boardwalk GP, LP $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)
Legal damages awarded to other party (approximately)	$ 690
Pre-judgment interest awarded to other party (approximately)	$ 166

Commitments and Contingencies_2

Commitments and Contingencies Letter of Credit Proceeds (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Letter of Credit Proceeds	$ 37.7	$ 27.7
Letter of Credit Proceeds Recognized into Transportation Revenue	$ 34.4	$ 26.2

Commitments and Contingencies E

Commitments and Contingencies Environmental and Safety Matters (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Accrual for Environmental Loss Contingencies	$ 3.8	$ 4.2
Number of years the related expenditures are expected to cover assessment and remediation costs (in years)	30 years
Accrued Environmental Loss Contingencies, Current	$ 1.3	1
Accrued Environmental Loss Contingencies, Noncurrent	$ 2.5	$ 3.2

Commitments and Contingencies C

Commitments and Contingencies Commitments for Construction (Details) $ in Millions	Dec. 31, 2021USD ($)
Commitments and Contingencies Disclosure [Abstract]
Purchase Commitment, Remaining Minimum Amount Committed	$ 95.3

Commitments and Contingencies P

Commitments and Contingencies Pipeline Capacity Agreements (Details) - Pipeline Capacity Agreements - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Recorded Unconditional Purchase Obligation [Line Items]
Expenses related to pipeline capacity agreements	$ 5.9	$ 4.2	$ 3.8
2022	2.7
2023	0
2024	0
2025	0
2026	0
Thereafter	$ 0

Fair Value Measurements Financi

Fair Value Measurements Financial Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2021		Dec. 31, 2020
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and Cash Equivalents, Fair Value	$ 39.1		$ 2.9
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Debt Instrument, Fair Value Disclosure	3,631.5		3,847.6
Finance Lease, Liability, Noncurrent	5.3		6.1
Unamortized debt issuance costs	4.8		5.8
Carrying Value
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and Cash Equivalents, Fair Value	39.1		2.9
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Debt Instrument, Fair Value Disclosure	3,334	[1]	3,460.4	[2]
Fair Value \| Fair Value, Inputs, Level 1
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and Cash Equivalents, Fair Value	39.1		2.9
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Debt Instrument, Fair Value Disclosure	0		0
Fair Value \| Fair Value, Inputs, Level 2
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and Cash Equivalents, Fair Value	0		0
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Debt Instrument, Fair Value Disclosure	3,631.5		3,847.6
Fair Value \| Fair Value, Inputs, Level 3
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and Cash Equivalents, Fair Value	0		0
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Debt Instrument, Fair Value Disclosure	0		0
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure, Recurring	0		0
Liabilities, Fair Value Disclosure, Recurring	$ 0		$ 0

[1]	The carrying amount of long-term debt excludes a $5.3 million long-term finance lease obligation and $4.8 million of unamortized debt issuance costs.
[2]	The carrying amount of long-term debt excludes a $6.1 million long-term finance lease obligation and $5.8 million of unamortized debt issuance costs.

Property, Plant and Equipment P

Property, Plant and Equipment Property, Plant and Equipment Class and Useful Life (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Total PPE	$ 12,488.1	$ 12,148.3
Less: accumulated depreciation	3,947	3,598.5
Total PPE, net	8,541.1	8,549.8
Depreciation expense for PPE	364.4	356.9	$ 344.2
Depreciable plant:
Property, Plant and Equipment [Line Items]
Total PPE	$ 12,051.1	$ 11,767.5
Weighted-Average Useful Lives (Years)	37 years	37 years
Depreciable plant: \| Transmission
Property, Plant and Equipment [Line Items]
Total PPE	$ 10,672.7	$ 10,417.9
Weighted-Average Useful Lives (Years)	37 years	37 years
Depreciable plant: \| Storage
Property, Plant and Equipment [Line Items]
Total PPE	$ 886.5	$ 863.5
Weighted-Average Useful Lives (Years)	38 years	38 years
Depreciable plant: \| Gathering
Property, Plant and Equipment [Line Items]
Total PPE	$ 109.6	$ 108
Weighted-Average Useful Lives (Years)	23 years	23 years
Depreciable plant: \| General
Property, Plant and Equipment [Line Items]
Total PPE	$ 228.6	$ 224.9
Weighted-Average Useful Lives (Years)	15 years	14 years
Depreciable plant: \| Rights of way and other
Property, Plant and Equipment [Line Items]
Total PPE	$ 153.7	$ 153.2
Weighted-Average Useful Lives (Years)	33 years	33 years
Non-depreciable:
Property, Plant and Equipment [Line Items]
Total PPE	$ 437	$ 380.8
Non-depreciable: \| Construction work in progress
Property, Plant and Equipment [Line Items]
Total PPE	239.5	184.2
Non-depreciable: \| Storage
Property, Plant and Equipment [Line Items]
Total PPE	152.3	152.3
Non-depreciable: \| Land
Property, Plant and Equipment [Line Items]
Total PPE	$ 45.2	$ 44.3

Property, Plant and Equipment U

Property, Plant and Equipment Undivided Interests (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Undivided Interest Property [Line Items]
Gross PPE Investment	$ 78.7	$ 69.8
Accumulated Depreciation	$ 28.3	26
Mobile Bay Pipeline
Undivided Interest Property [Line Items]
Undivided interest in pipeline	64.00%
Gross PPE Investment	$ 14.6	14.5
Accumulated Depreciation	$ 7.5	7.1
NGLs pipelines and facilities
Undivided Interest Property [Line Items]
Undivided interest in two ethylene wells	83.00%
Gross PPE Investment	$ 51.3	42.5
Accumulated Depreciation	10.4	8.8
Offshore and other assets
Undivided Interest Property [Line Items]
Gross PPE Investment	12.8	12.8
Accumulated Depreciation	$ 10.4	$ 10.1

Property, Plant and Equipment A

Property, Plant and Equipment Asset Purchases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Asset Acquisition, Purchase Price	$ 20
Bistineau Storage
Co-owner's interest in storage facility		8.00%
Purchase price to obtain co-owner's interest in storage facility		$ 18.8
Undivided interests in storage facility		100.00%

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 237.4	$ 237.4
Goodwill, Impairment Loss	$ 0	$ 0	$ 0

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Gross carrying amount	$ 59.4	$ 59.4
Accumulated amortization	(17.2)	(15.3)
Net carrying amount	42.2	44.1
Amortization of Intangible Assets	1.9	$ 1.9	$ 1.9
2022	1.9
2023	1.9
2024	2
2025	2
2026	2
Thereafter	$ 32.4
Finite-Lived Intangible Asset, Useful Life	22 years

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year	$ 63.1	$ 60.4
Liabilities recorded	9.5	1.3
Liabilities settled	(2.2)	(0.9)
Accretion expense	2.9	2.3
Revision of estimates	(8.4)	0
Balance at end of year	64.9	63.1
Less: Current portion of ARO	(3.4)	(8.2)
Long-term ARO	61.5	54.9
Provision for other asset retirement	$ 88.2	$ 81.6

Regulatory Assets and Liabili_3

Regulatory Assets and Liabilities Regulatory Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Regulatory Assets and Liabilities Disclosure [Abstract]
Period of recovery-minimum (in years)	1 year
Period of recovery-maximum (in years)	18 years
Regulatory Assets [Line Items]
Regulatory Assets	$ 15.8	$ 15.9
Pension
Regulatory Assets [Line Items]
Regulatory Assets	8.1	10.6
Tax effect of AFUDC equity
Regulatory Assets [Line Items]
Regulatory Assets	0.4	0.6
Fuel tracker
Regulatory Assets [Line Items]
Regulatory Assets	6.8	4.2
Other
Regulatory Assets [Line Items]
Regulatory Assets	$ 0.5	$ 0.5

Regulatory Assets and Liabili_4

Regulatory Assets and Liabilities Regulatory Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Regulatory Assets [Line Items]
Regulatory Assets	$ 15.8	$ 15.9
Regulatory Liabilities [Line Items]
Regulatory Liabilities	163.9	157
Cashout and fuel tracker
Regulatory Liabilities [Line Items]
Regulatory Liabilities	12.7	14.1
Provision for other asset retirement
Regulatory Liabilities [Line Items]
Regulatory Liabilities	88.2	81.6
Postretirement benefits other than pension
Regulatory Liabilities [Line Items]
Regulatory Liabilities	64.7	63.3
Unamortized debt issuance costs
Regulatory Assets [Line Items]
Regulatory Assets	1.5	1.8
Unamortized discount on long-term debt
Regulatory Assets [Line Items]
Regulatory Assets	$ 0.2	$ 0.2

Financing - Debt (Details)

Financing - Debt (Details) - USD ($) $ in Millions		Aug. 31, 2020	May 31, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Feb. 04, 2022
Debt Instruments [Abstract]
Finance lease obligation				$ 5.3	$ 6.1
Debt and Lease Obligation				3,355.3	3,486.1
Unamortized debt discount				(16)	(19.6)
Unamortized debt issuance costs				(4.8)	(5.8)
Long-term debt and finance lease obligation				3,334.5	3,460.7
Line of Credit Facility [Abstract]
Repayments of borrowings from long-term debt				0	$ 440	$ 350
Unsecured Debt
Debt Instruments [Abstract]
Long-term Debt, Gross				3,350
Long-term Debt, Fiscal Year Maturity [Abstract]
2022				300
2023				300
2024				600
2025				0
2026				550
Thereafter				$ 1,600
Debt, Weighted-Average Interest Rate				4.84%	4.84%
Debt Instrument, Redemption Price, Percentage - equal to the greater of				100.00%
Line of Credit Facility [Abstract]
Short-term Debt, Refinanced, Description				The Company has included the Gulf South Notes which mature in less than one year as long-term debt on its Consolidated Balance Sheets as of December 31, 2021. The Company has the intent and the ability to refinance the notes through the available borrowing capacity under its revolving credit facility as of December 31, 2021.
Debt Instrument, Redemption, Description				The Company's notes and debentures are redeemable, in whole or in part, at the Company's option at any time, at a redemption price equal to the greater of 100% of the principal amount of the notes to be redeemed or a “make whole” redemption price based on the remaining scheduled payments of principal and interest discounted to the date of redemption at a rate equal to the Treasury rate plus 20 to 50 basis points depending upon the particular issue of notes, plus accrued and unpaid interest, if any. Other customary covenants apply, including those concerning events of default.
Debt Instrument, Covenant Description				The indentures governing the notes and debentures have restrictive covenants which provide that, with certain exceptions, neither the Company nor any of its subsidiaries may create, assume or suffer to exist any lien upon any property to secure any indebtedness unless the debentures and notes shall be equally and ratably secured. All of the Company's debt obligations are unsecured.
Debt Instrument, Covenant Compliance				As of December 31, 2021, Boardwalk Pipelines and its operating subsidiaries were in compliance with their debt covenants.
Unsecured Debt \| Boardwalk Pipelines 3.375% Notes Due 2023
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 300	$ 300
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage				3.375%	3.375%
Unsecured Debt \| Boardwalk Pipelines 4.95% Notes Due 2024
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 600	$ 600
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage				4.95%	4.95%
Unsecured Debt \| Boardwalk Pipelines 5.95% Notes Due 2026
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 550	$ 550
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage				5.95%	5.95%
Unsecured Debt \| Boardwalk Pipelines 4.45% Notes Due 2027
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 500	$ 500
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage				4.45%	4.45%
Unsecured Debt \| Boardwalk Pipelines 4.8% Notes Due 2029
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 500	$ 500
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Issuance Date			May 31, 2019
Debt Instrument, Face Amount			$ 500
Payments of Debt Issuance Costs			4.8
Proceeds from Debt, Net of Issuance Costs	[1]		$ 495.2
Debt Instrument, Interest Rate, Stated Percentage			4.80%	4.80%	4.80%
Debt Instrument, Maturity Date			May 3, 2029
Unsecured Debt \| Boardwalk Pipelines 3.40% Notes Due 2031
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 500	$ 500
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Issuance Date		Aug. 31, 2020
Debt Instrument, Face Amount		$ 500
Payments of Debt Issuance Costs		5
Proceeds from Debt, Net of Issuance Costs	[2]	$ 495
Debt Instrument, Interest Rate, Stated Percentage		3.40%		3.40%
Debt Instrument, Maturity Date		Feb. 15, 2031
Unsecured Debt \| Gulf South 4.00% Notes Due 2022
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 300	$ 300
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage				4.00%	4.00%
Short-term Debt, Refinanced, Amount				$ 300
Unsecured Debt \| Texas Gas 7.25% Debentures Due 2027
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 100	$ 100
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage				7.25%	7.25%
Unsecured Debt \| Total Notes and Debentures
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 3,350	$ 3,350
Unsecured Debt \| Texas Gas 4.50% Notes Due 2021
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage					4.50%
Line of Credit Facility [Abstract]
Repayments of borrowings from long-term debt					$ 440
Unsecured Debt \| Boardwalk Pipelines 5.75% Notes Due 2019
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt Instrument, Interest Rate, Stated Percentage						5.75%
Line of Credit Facility [Abstract]
Repayments of borrowings from long-term debt						$ 350
Line of Credit
Long-term Debt, Fiscal Year Maturity [Abstract]
Debt, Weighted-Average Interest Rate					1.39%
Line of Credit Facility [Abstract]
Maximum Ratio of Debt to EBITDA				5.0 to 1.0
Maximum Ratio of Debt to EBITDA after Acquisition				5.5 to 1.0
Qualified Acquisition Purchase Price Target (greater than)				$ 100
Long-term Line of Credit				0	$ 130
Line of Credit Facility, Remaining Borrowing Capacity				$ 1,000
Line of Credit Facility, Covenant Terms				The Credit Agreement contains various restrictive covenants and other usual and customary terms and conditions, including restrictions regarding the incurrence of additional debt, the sale of assets and sale-leaseback transactions. The financial covenants under the Credit Agreement require the Company and its subsidiaries to maintain, among other things, a ratio of total consolidated debt to consolidated EBITDA (as defined in the Credit Agreement) measured for the previous twelve months of not more than 5.0 to 1.0, or up to 5.5 to 1.0 for (i) the quarter in which the consummation of a qualified acquisition or series of acquisitions, where the purchase price exceeds $100.0 million over a rolling 12-month period and (ii) the three quarters following the qualified acquisition quarter.
Line of Credit Facility, Covenant Compliance				The Company and its subsidiaries were in compliance with all covenant requirements under the Credit Agreement as of December 31, 2021.
Line of Credit \| Subsequent Event
Line of Credit Facility [Abstract]
Long-term Line of Credit							$ 0
Line of Credit Facility, Remaining Borrowing Capacity							$ 1,000
Line of Credit \| Minimum
Line of Credit Facility [Abstract]
Line of Credit Facility, Commitment Fee Percentage				0.10%
Line of Credit \| Maximum
Line of Credit Facility [Abstract]
Line of Credit Facility, Commitment Fee Percentage				0.275%
Line of Credit \| Base Rate
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis				base rate
Line of Credit \| Base Rate \| Minimum
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate				0.00%
Line of Credit \| Base Rate \| Maximum
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate				0.75%
Line of Credit \| Prime Rate
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis				prime rate
Line of Credit \| Federal Funds Effective Swap Rate
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis				federal funds
Debt Instrument, Basis Spread on Variable Rate				0.50%
Line of Credit \| Eurodollar
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis				one month Eurodollar Rate
Debt Instrument, Basis Spread on Variable Rate				1.00%
Line of Credit \| London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis				LIBOR
Line of Credit \| London Interbank Offered Rate (LIBOR) \| Minimum
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate				1.00%
Line of Credit \| London Interbank Offered Rate (LIBOR) \| Maximum
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate				1.75%
Line of Credit \| Gulf South Revolving Credit Facility
Debt Instruments [Abstract]
Long-term Debt, Gross				$ 0	30
Line of Credit \| Texas Gas Revolving Credit Facility
Debt Instruments [Abstract]
Long-term Debt, Gross				0	$ 100
Line of Credit \| Amendment No. 3 Credit Agreement - 2021
Line of Credit Facility [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity				$ 1,000
Line of Credit Facility, Expiration Date				May 27, 2026
Maturity date extension term				2 years

[1]	The net proceeds of this offering were used to retire the outstanding $350.0 million aggregate principal amount of Boardwalk Pipelines 5.75% notes due 2019 at maturity and for general partnership purposes.
[2]	The net proceeds of this offering were used to retire the outstanding $440.0 million aggregate principal amount of Texas Gas 4.50% notes due 2021 on November 3, 2020, to fund growth capital expenditures and for general partnership purposes.

Financing Cash Distributions (D

Financing Cash Distributions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Distributions Made to Members or Limited Partners [Abstract]
Partners' Capital Account, Distributions	$ 102.2	$ 102.2	$ 102.2

Employee Benefits (Details)

Employee Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Employee Benefits (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Contribution Plan, Cost	$ 12.8	$ 11.9	$ 11.5
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Required amount of funding of periodic pension cost	3
Contribution to defined benefit pension plan	5.2	3.6
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	3
Minimum amount of recognized expense each year associated with retirement plan	$ 3
Future rate recovery	in excess of $6.0 million
Precluded future recovery of annual pension costs, lower range	$ 3
Precluded future recovery of annual pension costs, upper range	$ 6
Recognition of regulatory assets (in excess of)	in excess of $6.0 million
Reduction of regulatory assets (less than)	less than $3.0 million
Pension plan costs charged to expense, lower range	$ 3
Pension plan costs charged to expense, upper range	6
PBOP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contribution to defined benefit pension plan	0.1	0.1
Plan assets expected to be returned to employer	0
PBOP \| Defined Benefit Plan, Overfunded Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	0
SRP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contribution to defined benefit pension plan	$ 0	$ 0

Employee Benefits, Projected Be

Employee Benefits, Projected Benefit Obligation, Fair Value of Assets, Funded Status and the Amounts Not Yet Recognized As Components of Net Periodic Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Retirement Plans
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of period	$ 120.7	$ 122.2
Service cost	2.6	2.8	$ 3
Interest cost	2.1	2.7	3.9
Plan participants' contributions	0	0
Actuarial (gain) loss	(1.4)	6
Benefits paid	(0.5)	(0.5)
Settlements	(14.4)	(12.5)
Benefit obligation at end of period	109.1	120.7	122.2
Change in Plan Assets [Roll Forward]
Fair value of plan assets at beginning of period	102.7	101.7
Actual return on plan assets	10.5	10.4
Company's contribution	5.2	3.6
Plan participants' contributions	0	0
Benefits paid	(0.5)	(0.5)
Settlements	(14.4)	(12.5)
Fair value of plan assets at end of period	103.5	102.7	101.7
Funded status	(5.6)	(18)
Items Not Recognized As Components Of Net Periodic Cost [Abstract]
Net actuarial loss (gain)	10	18.2
PBOP
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of period	35.2	36.5
Service cost	0.1	0.1	0.1
Interest cost	0.9	1.1	1.4
Plan participants' contributions	1.1	1.1
Actuarial (gain) loss	(2.6)	(0.3)
Benefits paid	(4.1)	(3.3)
Settlements	0	0
Benefit obligation at end of period	30.6	35.2	36.5
Change in Plan Assets [Roll Forward]
Fair value of plan assets at beginning of period	96.2	90.8
Actual return on plan assets	(0.3)	7.5
Company's contribution	0.1	0.1
Plan participants' contributions	1.1	1.1
Benefits paid	(4.1)	(3.3)
Settlements	0	0
Fair value of plan assets at end of period	93	96.2	$ 90.8
Funded status	62.4	61
Items Not Recognized As Components Of Net Periodic Cost [Abstract]
Net actuarial loss (gain)	$ (2.9)	$ (3.4)

Employee Benefits, Aggregate In

Employee Benefits, Aggregate Information Related Only to the Underfunded Plans (Details) - Retirement Plans - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
Projected benefit obligation	$ 109.1	$ 120.7
Accumulated benefit obligation	103.4	113.7
Fair value of plan assets	$ 103.5	$ 102.7

Employee Benefits, Components o

Employee Benefits, Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Retirement Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 2.6	$ 2.8	$ 3
Interest cost	2.1	2.7	3.9
Expected return on plan assets	(6.2)	(6.3)	(6.4)
Amortization of unrecognized net loss	0.8	1.9	2.2
Settlement charge	1.6	2.4	2.9
Regulatory asset decrease	2.5	0	0
Net periodic benefit cost	3.4	3.5	5.6
PBOP
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	0.1	0.1	0.1
Interest cost	0.9	1.1	1.4
Expected return on plan assets	(2.7)	(3.2)	(3)
Amortization of unrecognized net loss	0	0	0
Settlement charge	0	0	0
Net periodic benefit cost	$ (1.7)	$ (2)	$ (1.5)
Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Future rate recovery	in excess of $6.0 million

Employee Benefits, Estimated Fu

Employee Benefits, Estimated Future Benefit Payments (Details) $ in Millions	Dec. 31, 2021USD ($)
Retirement Plans
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2022	$ 21.8
2023	11.9
2024	10.7
2025	11.9
2026	10.1
2027-2031	34.5
PBOP
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2022	2.1
2023	2.1
2024	2
2025	1.9
2026	1.9
2027-2031	$ 7.5

Employee Benefits, Weighted-Ave

Employee Benefits, Weighted-Average Assumptions Used to Determine Benefit Obligations (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Pension Plan
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate (percent)	2.30%	1.70%
Expected return on plan assets (percent)	6.25%	6.50%
Rate of compensation increase (percent)	3.00%	3.00%
SRP
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate (percent)	2.35%	1.55%
Expected return on plan assets (percent)	6.25%	6.50%
Rate of compensation increase (percent)	3.00%	3.00%
PBOP
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate (percent)	2.90%	2.60%
Expected return on plan assets (percent)	2.01%	2.81%

Employee Benefits, Weighted-A_2

Employee Benefits, Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost (Details)		3 Months Ended												12 Months Ended
		Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Plan
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate (percent)	[1]	2.30%	1.95%	2.05%	2.05%	1.70%	1.85%	2.20%	2.95%	2.70%	2.60%	3.25%	3.80%
Expected return on plan assets (percent)														6.50%	7.00%	7.00%
Rate of compensation increase (percent)														3.00%	3.00%	3.86%
SRP
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate (percent)														1.55%	2.70%	4.10%
Expected return on plan assets (percent)														6.50%	7.00%	7.00%
Rate of compensation increase (percent)														3.00%	3.00%	3.86%
PBOP
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate (percent)														2.60%	3.30%	4.30%
Expected return on plan assets (percent)														2.81%	3.61%	3.61%

[1]	Pension expense was remeasured quarterly in 2021, 2020 and 2019. The quarterly remeasurements for each quarter in 2021, 2020 and 2019 were as follows: Quarter 1: 2.05%, 2.95% and 3.80%; Quarter 2: 2.05%, 2.20% and 3.25%; Quarter 3: 1.95%, 1.85% and 2.60%; and Quarter 4: 2.30%, 1.70% and 2.70%.

Employee Benefits, Master Trust

Employee Benefits, Master Trust Pension and PBOP Fair Value Hierarchy (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Amount committed to future capital calls in exchange for an ownership interest	$ 2
PBOP
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	$ 93	$ 96.2	$ 90.8
Allocation to fixed income securities	100.00%	100.00%
PBOP \| Short-term investments
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	$ 4.3	$ 5.7
PBOP \| Fixed income mutual funds
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	19.2	19.5
PBOP \| Asset-backed securities
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	6.9	14.4
PBOP \| Corporate Bond Securities
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	31	23.7
PBOP \| Tax Exempt Securities
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	31.6	32.9
Retirement Plans
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	$ 103.5	$ 102.7	$ 101.7
Master Trust percentage of pension plan assets	43.20%	43.90%
Fair Value, Measurements, Recurring \| Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	$ 184.5	$ 176.3
Investments, Excluding Net Asset Value, Fair Value Disclosure	184.5	176.3
Alternative Investment	54.9	57.5
Investments, Fair Value Disclosure	239.4	233.8
Fair Value, Measurements, Recurring \| Pension Plan \| Fair Value, Inputs, Level 1
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	184.5	176.3
Fair Value, Measurements, Recurring \| Pension Plan \| Fair Value, Inputs, Level 2
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| Pension Plan \| Fair Value, Inputs, Level 3
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| Pension Plan \| Equity securities
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	69.1	59.9
Fair Value, Measurements, Recurring \| Pension Plan \| Equity securities \| Fair Value, Inputs, Level 1
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	69.1	59.9
Fair Value, Measurements, Recurring \| Pension Plan \| Equity securities \| Fair Value, Inputs, Level 2
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| Pension Plan \| Equity securities \| Fair Value, Inputs, Level 3
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| Pension Plan \| Short-term investments
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	1.9	3.9
Fair Value, Measurements, Recurring \| Pension Plan \| Short-term investments \| Fair Value, Inputs, Level 1
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	1.9	3.9
Fair Value, Measurements, Recurring \| Pension Plan \| Short-term investments \| Fair Value, Inputs, Level 2
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| Pension Plan \| Short-term investments \| Fair Value, Inputs, Level 3
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| Pension Plan \| Other assets
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	2.2
Fair Value, Measurements, Recurring \| Pension Plan \| Other assets \| Fair Value, Inputs, Level 1
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	2.2
Fair Value, Measurements, Recurring \| Pension Plan \| Fixed income mutual funds
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	111.3	112.5
Fair Value, Measurements, Recurring \| Pension Plan \| Fixed income mutual funds \| Fair Value, Inputs, Level 1
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	111.3	112.5
Fair Value, Measurements, Recurring \| Pension Plan \| Fixed income mutual funds \| Fair Value, Inputs, Level 2
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| Pension Plan \| Fixed income mutual funds \| Fair Value, Inputs, Level 3
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| PBOP \| Fair Value, Inputs, Level 1
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	23.5	25.2
Fair Value, Measurements, Recurring \| PBOP \| Fair Value, Inputs, Level 2
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	69.5	71
Fair Value, Measurements, Recurring \| PBOP \| Fair Value, Inputs, Level 3
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| PBOP \| Short-term investments \| Fair Value, Inputs, Level 1
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	4.3	5.7
Fair Value, Measurements, Recurring \| PBOP \| Short-term investments \| Fair Value, Inputs, Level 2
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| PBOP \| Short-term investments \| Fair Value, Inputs, Level 3
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| PBOP \| Fixed income mutual funds \| Fair Value, Inputs, Level 1
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	19.2	19.5
Fair Value, Measurements, Recurring \| PBOP \| Fixed income mutual funds \| Fair Value, Inputs, Level 2
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| PBOP \| Fixed income mutual funds \| Fair Value, Inputs, Level 3
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| PBOP \| Asset-backed securities \| Fair Value, Inputs, Level 1
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| PBOP \| Asset-backed securities \| Fair Value, Inputs, Level 2
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	6.9	14.4
Fair Value, Measurements, Recurring \| PBOP \| Asset-backed securities \| Fair Value, Inputs, Level 3
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| PBOP \| Corporate Bond Securities \| Fair Value, Inputs, Level 1
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| PBOP \| Corporate Bond Securities \| Fair Value, Inputs, Level 2
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	31	23.7
Fair Value, Measurements, Recurring \| PBOP \| Corporate Bond Securities \| Fair Value, Inputs, Level 3
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| PBOP \| Tax Exempt Securities \| Fair Value, Inputs, Level 1
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fair Value, Measurements, Recurring \| PBOP \| Tax Exempt Securities \| Fair Value, Inputs, Level 2
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	31.6	32.9
Fair Value, Measurements, Recurring \| PBOP \| Tax Exempt Securities \| Fair Value, Inputs, Level 3
Defined Contribution Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0
Minimum \| Pension Plan \| Equity securities
Defined Contribution Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations Range (up to)	40.00%
Minimum \| Pension Plan \| Alternative Investments
Defined Contribution Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations Range (up to)	40.00%
Maximum \| Pension Plan \| Equity securities
Defined Contribution Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations Range (up to)	60.00%
Maximum \| Pension Plan \| Alternative Investments
Defined Contribution Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations Range (up to)	60.00%

Employee Benefits Employee Bene

Employee Benefits Employee Benefits, 2018 LTIP (Details) - Performance Awards - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred Compensation Arrangement with Individual, Cash Award Granted, Amount	$ 12.4	$ 12.2
Deferred Compensation Arrangement with Individual, Compensation Expense	12.7	10.9	$ 6.1
Unrecognized compensation expense related to the Performance Awards	$ 7	$ 7
Minimum
Stated Target Amount Adjustment Range	90.00%
Maximum
Stated Target Amount Adjustment Range	110.00%

Employee Benefits, LTIP and UAR

Employee Benefits, LTIP and UAR and Cash Bonus Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
LTIP and UAR and Cash Bonus Plan
Deferred Compensation and Share-based Compensation, Expense	$ 1.4	$ 6.2

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
State and Local Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current expense: State	$ 0.5	$ 0.1	$ 0.4
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred provision: State	0.2	0.2	0.1
Income taxes	$ 0.7	0.3	0.5
Open Tax Year	2018 2019 2020 2021
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	$ 0	0	$ 0
Deferred Tax Assets, Net (Significant)	$ 0	$ 0

Credit Risk (Details)

Credit Risk (Details) MMBbls in Millions, MMBTU in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)$ / MMBTUMMBTUMMBbls	Dec. 31, 2020USD ($)$ / MMBTUMMBTUMMBbls	Dec. 31, 2019USD ($)
Concentration Risk [Line Items]
Operating revenues	$ 1,340.1	$ 1,297.6	$ 1,295.2
Gas loaned to customers [Abstract]
Gas Balancing Measurement (in MMBtu) \| MMBTU	7.4	11.2
Average Market Price Of Gas Assumed \| $ / MMBTU	3.59	2.45
Gas Imbalance To Subsidiaries Asset Liability	$ 26.6	$ 27.4
Natural Gas Liquids Balancing Volume (in MMBbls) \| MMBbls	0	0
Customer Concentration Risk
Concentration Risk [Line Items]
Operating revenues		$ 132.5
Concentration Risk, Benchmark Description	total operating revenues
Customer Concentration Risk \| Revenue Benchmark
Concentration Risk [Line Items]
Concentration risk, percentage (approximately)		10.00%

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	$ 5.5	$ 5.7	$ 5.7
Boardwalk GP, LP
Related Party Transaction [Line Items]
Cash dividends paid to parent company	$ 102.2	$ 102.2	$ 102.2