Boardwalk Pipeline Partners (BWP) 10-Q4 Nov 242024 Q3 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2024	Nov. 04, 2024
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	01-32665
Entity Registrant Name	BOARDWALK PIPELINE PARTNERS, LP
Entity Incorporation, State	DE
Entity Tax Identification Number	20-3265614
Entity Address, Address Line One	9 Greenway Plaza,
Entity Address, Address Line Two	Suite 2800
Entity Address, City	Houston,
Entity Address, State	TX
Entity Address, Postal Zip Code	77046
City Area Code	(866)
Local Phone Number	913-2122
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
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001336047
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		0

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Current Assets:
Cash and cash equivalents	$ 255.9	$ 20.1
Receivables:
Trade, net	161.2	204.6
Other	17.8	24.9
Gas transportation receivables	7	7
Prepayments	30.2	24.3
Short-term investments	603.1	0
Total current assets	1,103	288.7
Property, Plant and Equipment:
Property, plant and equipment, gross	13,760.2	13,529.5
Less—accumulated depreciation and amortization	4,946.6	4,672.9
Property, plant and equipment, net	8,813.6	8,856.6
Other Assets:
Goodwill	237.4	237.4
Gas stored underground	89.6	99.3
Other	226.8	214.4
Total other assets	553.8	551.1
Total Assets	10,470.4	9,696.4
Payables:
Trade	69.9	113.2
Gas transportation payables	5.2	7.8
Accrued taxes, other	90.7	67.9
Accrued interest	44.8	34.2
Accrued payroll and employee benefits	44.9	44
Current portion of long-term debt	599.8	0
Other current liabilities	49.5	75.4
Total current liabilities	931.5	362.3
Long-term debt and finance lease obligation	3,233.6	3,261.9
Other Liabilities and Deferred Credits:
Pension liability	4	4.7
Asset retirement obligations	60.4	59.2
Provision for other asset retirement	103.1	98.1
Other	127.8	119.1
Total other liabilities and deferred credits	295.3	281.1
Commitments and Contingencies
Partners' Capital:
Partners' capital	6,086.5	5,867.7
Accumulated other comprehensive loss	(76.5)	(76.6)
Total partners' capital	6,010	5,791.1
Total Liabilities and Partners' Capital	10,470.4	9,696.4
Affiliates
Receivables:
Other current assets	7.7	0.2
Payables:
Payables	12.9	3.4
Other
Receivables:
Other current assets	20.1	7.6
Payables:
Payables	13.8	16.4
Natural gas transmission and other plant
Property, Plant and Equipment:
Property, plant and equipment, gross	13,564.2	13,242.3
Construction work in progress
Property, Plant and Equipment:
Property, plant and equipment, gross	$ 196	$ 287.2

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Operating Revenues:
Transportation	$ 315.1	$ 299.7	$ 983.6	$ 940.9
Storage, parking and lending	54.1	39.5	157.2	115.5
Product sales	84.3	0	263.1	0.8
Other	20	16.5	57.6	51.5
Total operating revenues	473.5	355.7	1,461.5	1,108.7
Operating Costs and Expenses:
Costs associated with service revenues	6.4	7	20.2	19.6
Costs associated with product sales	62.7	0	205.4	0
Operation and maintenance	78.2	73.8	216.2	201.5
Administrative and general	45.6	44.2	137.8	126.7
Depreciation and amortization	105.7	101.9	317.7	302.9
(Gain) loss on sale of assets, impairments and other	1.2	0	(6.5)	0.1
Taxes other than income taxes	30.2	27.8	90.6	88
Total operating costs and expenses	330	254.7	981.4	738.8
Operating income	143.5	101	480.1	369.9
Other Deductions (Income):
Interest expense	46.8	38.7	137	116.7
Interest income	(9.7)	(5.7)	(22.2)	(11.7)
Miscellaneous other income, net	(0.4)	(1.3)	(4.3)	(2.6)
Total other deductions	36.7	31.7	110.5	102.4
Income before income taxes	106.8	69.3	369.6	267.5
Income taxes	0.2	0.1	0.8	0.6
Net income	$ 106.6	$ 69.2	$ 368.8	$ 266.9

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 106.6	$ 69.2	$ 368.8	$ 266.9
Other comprehensive income:
Reclassification adjustment transferred to Net income from cash flow hedges	0	0	0.1	0.1
Pension and other postretirement benefit costs, net of tax	0	0.2	0	1.5
Total Comprehensive Income	$ 106.6	$ 69.4	$ 368.9	$ 268.5

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Operating Activities:
Net income	$ 368.8	$ 266.9
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	317.7	302.9
Amortization of deferred costs and other	(5.1)	15.7
(Gain) loss on sale of assets, impairments and other	(6.5)	0.1
Changes in operating assets and liabilities:
Trade and other receivables	48.8	28.5
Gas receivables and payables and product inventory	(18.5)	(1.3)
Prepayments and other assets	(12)	(4.6)
Trade and other payables	(21.7)	(5.1)
Other payables, affiliates	0.1	0.1
Accrued liabilities	33.4	31.1
Other liabilities	(8.2)	(5)
Net cash provided by operating activities	696.8	629.3
Investing Activities:
Capital expenditures	(291.9)	(231.9)
Proceeds from sale of operating assets	0.4	0.2
Advances to affiliates	(7.5)	0
Acquisition of business	0	(347.6)
Purchases of short-term investments	(1,102.2)	0
Proceeds from the maturity of short-term investments	513	0
Net cash used in investing activities	(888.2)	(579.3)
Financing Activities:
Proceeds from long-term debt, net of issuance cost	593.5	0
Proceeds from borrowings on revolving credit facility	170	0
Repayments of borrowings on revolving credit facility, including financing fees	(195)	(0.6)
Principal payment of finance lease obligation	(0.7)	(0.6)
Advances from affiliates	9.4	0.6
Distributions paid	(150)	0
Net cash provided by (used in) financing activities	427.2	(0.6)
Increase in cash and cash equivalents	235.8	49.4
Cash and cash equivalents at beginning of period	20.1	215.6
Cash and cash equivalents at end of period	$ 255.9	$ 265

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN PARTNERS' CAPITAL (Unaudited) - USD ($) $ in Millions	Total	Accumulated Other Comprehensive (Loss) Income	Partners' Capital
Beginning balance at Dec. 31, 2022	$ 5,702.2	$ (79.5)	$ 5,781.7
Add (deduct):
Net income	266.9		266.9
Other comprehensive income, net of tax	1.6	1.6
Ending balance at Sep. 30, 2023	5,970.7	(77.9)	6,048.6
Beginning balance at Jun. 30, 2023	5,901.3	(78.1)	5,979.4
Add (deduct):
Net income	69.2		69.2
Other comprehensive income, net of tax	0.2	0.2
Ending balance at Sep. 30, 2023	5,970.7	(77.9)	6,048.6
Beginning balance at Dec. 31, 2023	5,791.1	(76.6)	5,867.7
Add (deduct):
Net income	368.8		368.8
Distributions paid	(150)		(150)
Other comprehensive income, net of tax	0.1	0.1
Ending balance at Sep. 30, 2024	6,010	(76.5)	6,086.5
Beginning balance at Jun. 30, 2024	5,953.4	(76.5)	6,029.9
Add (deduct):
Net income	106.6		106.6
Distributions paid	(50)		(50)
Ending balance at Sep. 30, 2024	$ 6,010	$ (76.5)	$ 6,086.5

Basis of Presentation

Basis of Presentation	9 Months Ended
Basis of Presentation	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation 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, which consists of integrated pipeline and storage systems for natural gas and natural gas liquids and other hydrocarbons (herein referred to together as NGLs). As of September 30, 2024, Boardwalk Pipelines Holding Corp. (BPHC), a wholly owned subsidiary of Loews Corporation (Loews), owned directly or indirectly, 100% of the Company's capital. The accompanying unaudited condensed consolidated financial statements of the Company have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America (U.S.) (GAAP) have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments (consisting of only normal recurring accruals) necessary to present fairly the Company's financial position as of September 30, 2024, and December 31, 2023, its results of operations, comprehensive income and changes in partners' capital for the three and nine months ended September 30, 2024 and 2023, and its changes in cash flows for the nine months ended September 30, 2024 and 2023, in each case in accordance with GAAP. Reference is made to the Notes to the Consolidated Financial Statements in the Company's Annual Report on Form 10-K for the year ended December 31, 2023 (2023 Annual Report on Form 10-K), which should be read in conjunction with these unaudited condensed consolidated financial statements. The accounting policies described in Note 2 of Part II, Item 8. of the Company's 2023 Annual Report on Form 10-K are the same policies that were used in preparing the accompanying unaudited condensed consolidated financial statements. Results of operations for interim periods may not necessarily be indicative of results for the full year. Certain amounts reported in Other revenues were reclassified to Product sales to conform to the current presentation in connection with the acquisition discussed in Note 2. The amounts reclassified represent NGL product sales that occurred during 2023. Costs associated with these product sales were immaterial. The effect of the reclassification was a decrease in Other revenues and an increase in Product sales of $0.8 million for 2023. This reclassification had no impact on Total operating revenues , Operating income or Net income . Short-Term Investment Accounting Policy The Company has invested in short-term investments that have been classified as held-to-maturity as the Company has the intent and the ability to hold the short-term investments until they mature. As of September 30, 2024, the Company had recorded $603.1 million of U.S. treasury bills on its Condensed Consolidated Balance Sheets, maturing in December 2024, at amortized cost. The carrying amount of the U.S. treasury bills was adjusted for the accretion of discounts over the remaining life of the investment. Income related to the U.S. treasury bills was recorded in Interest Income on the Condensed Consolidated Statements of Income. As of September 30, 2024, the U.S. treasury bills had unrecognized gains of $0.6 million.

Acquisition

Acquisition	9 Months Ended
Acquisition	Sep. 30, 2024
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Acquisition	Acquisition On September 29, 2023, Boardwalk Resources Company, LLC, a wholly owned subsidiary of the Company, acquired Williams Olefins Pipeline Holdco LLC, renamed Boardwalk Ethane Pipeline Holdco, LLC (Bayou Ethane) after the acquisition, from Williams Field Services Group, LLC for $355.0 million in cash. Pro Forma Financial Information The following unaudited pro forma results of operations of the Company are presented as if the acquisition occurred on January 1, 2023. Such results are not necessarily indicative of future results. These pro forma results also do not reflect any cost savings, operating synergies or revenue enhancements that the Company may achieve or the costs necessary to achieve those objectives (in millions): Pro Forma For the For the Operating revenues $ 497.9 $ 1,453.8 Net income 76.2 274.6 The pro forma information was adjusted for the following items: • Operating revenues and costs were based on actual results for the periods indicated. Acquisition costs were not material and were excluded; and • Depreciation and amortization expense was calculated using property, plant and equipment (PPE) and intangible asset amounts as determined by the purchase price allocation and estimated useful lives.

Revenues

Revenues	9 Months Ended
Revenues	Sep. 30, 2024
Revenue from Contract with Customer [Abstract]
Revenues	Revenues The Company operates in one reportable segment. It contracts directly with end-use customers, including electric power generators, local distribution companies, industrial users and exporters of liquefied natural gas. The Company also contracts with other customers, including producers and marketers of natural gas and 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 (in millions): For the For the 2024 2023 2024 2023 Revenues from Contracts with Customers Firm Service (1)(2) $ 413.3 $ 330.4 $ 1,258.3 $ 1,030.3 Interruptible Service 15.0 13.0 47.0 41.1 Other revenues (2) 34.9 3.6 125.9 11.5 Total Revenues from Contracts with Customers 463.2 347.0 1,431.2 1,082.9 Other operating revenues (2)(3) 10.3 8.7 30.3 25.8 Total Operating Revenues $ 473.5 $ 355.7 $ 1,461.5 $ 1,108.7 (1) Revenues earned from contracts with minimum volume commitments (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. (2) For the three and nine months ended September 30, 2024, revenues attributable to Bayou Ethane were $53.9 million and $150.0 million included in firm service from product sales earned from contracts with MVCs; $20.6 million and $91.4 million included in other revenues from product sales earned from contracts with no MVCs; and $1.5 million and $3.8 million included in other operating revenues. (3) 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 September 30, 2024, and December 31, 2023, the Company had receivables recorded in Trade Receivables, net from contracts with customers of $161.2 million and $204.6 million, contract assets recorded in Other Assets from contracts with a customer of $10.8 million and $6.2 million, and contract liabilities recorded in Other Current Liabilities (current portion) and Other Liabilities (noncurrent portion) from contracts with customers of $19.8 million and $21.4 million. As of September 30, 2024, contract liabilities are expected to be recognized through 2040. Significant changes in the contract liability balances during the nine months ended September 30, 2024, were as follows (in millions): Contract Liabilities Balance as of December 31, 2023 (1) $ 21.4 Revenues recognized that were included in the contract liability (3.5) Increases due to cash received, excluding amounts recognized as 1.9 Balance as of September 30, 2024 (1) $ 19.8 (1) As of September 30, 2024, and December 31, 2023, $3.3 million and $3.5 million were recorded in Other Current Liabilities (current portion), and $16.5 million and $17.9 million were recorded in Other Liabilities (noncurrent portion). Significant changes in the contract liability balances during the nine months ended September 30, 2023, were as follows (in millions): Contract Liabilities Balance as of December 31, 2022 (1) $ 23.0 Revenues recognized that were included in the contract liability (3.0) Increases due to cash received, excluding amounts recognized as 1.6 Other 0.6 Balance as of September 30, 2023 (1) $ 22.2 (1) As of September 30, 2023, and December 31, 2022, $3.7 million and $3.6 million were recorded in Other Current Liabilities (current portion), and $18.5 million and $19.4 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 September 30, 2024. 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, or at a point in time as guaranteed minimum fees associated with the performance obligation are satisfied under certain ethane supply contracts. For the Company's customers that are charged maximum tariff rates related to its Federal Energy Regulatory Commission (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 variable nature of such services; (b) unsatisfied performance obligations from the ethane commodity indexed portion of ethane supply contracts because of the variable nature of ethane prices, and (c) consideration in contracts that is recognized in revenue as invoiced, such as for interruptible services. 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 2024 (1) 2025 Thereafter Total Estimated revenues from contracts with customers from unsatisfied performance obligations as of September 30, 2024 $ 397.0 $ 1,449.0 $ 8,962.5 $ 10,808.5 Operating revenues which are fixed and 7.0 27.5 163.0 197.5 Total projected operating revenues under committed firm agreements as of September 30, 2024 (2) $ 404.0 $ 1,476.5 $ 9,125.5 $ 11,006.0 (1) The 2024 period is for the remaining three months ending December 31, 2024. For the nine months ended September 30, 2024, the Company recognized $1,084.5 million of fixed fee revenues for the fulfillment of performance obligations. (2) In March 2024, the Company executed a 108-year firm storage agreement with a customer. The estimated annual revenue from this contract is $3.1 million, with $331.6 million of unsatisfied performance obligations included in the “Thereafter” column. Per the tariff provisions, this customer was required to provide 90 days of collateral and the Company can suspend services due to non-payment.

Gas and Liquids Stored Undergro

Gas and Liquids Stored Underground and Gas and NGLs Receivables and Payables	9 Months Ended
	Sep. 30, 2024
Oil and Gas, Gas-Balancing Arrangement [Abstract]
Gas and liquids stored underground and gas and NGLs receivables and payables	Gas and Liquids Stored Underground and Gas and NGLs Receivables and Payables The operating subsidiaries of the Company provide storage services whereby they store natural gas or NGLs on behalf of customers and also periodically hold customer gas under parking and lending (PAL) services. Since the customers retain title to the gas or NGLs held by the Company in providing these services, the Company does not record the related gas or NGLs on its Condensed Consolidated Balance Sheets. The operating subsidiaries of the Company also periodically lend gas to customers under PAL and certain firm services, and lend ethylene to customers under exchange agreements, and gas or NGLs may be owed to the Company's operating subsidiaries as a result of transportation imbalances. As of September 30, 2024, the amount of gas owed to the Company's operating subsidiaries due to gas imbalances and gas loaned under PAL and certain firm service agreements was approximately 6.7 trillion British thermal units (TBtu). Assuming an average market price during September 2024 of $2.17 per million British thermal unit (MMBtu), the market value of that gas was approximately $14.5 million. As of September 30, 2024, the amount of ethylene owed to the Company’s operating subsidiaries from ethylene loaned under exchange agreements was approximately 34.0 million pounds. Assuming an average market price during September 2024 of $0.21 per pound, the market value of that ethylene was approximately $7.1 million. As of December 31, 2023, the amount of gas owed to the Company's operating subsidiaries due to gas imbalances and gas loaned under PAL and certain firm service agreements was approximately 11.2 TBtu. Assuming an average market price during December 2023 of $2.33 per MMBtu, the market value of that gas was approximately $26.1 million. There were no amounts of ethylene owed to the Company's operating subsidiaries under exchange agreements as of December 31, 2023. As of September 30, 2024, and December 31, 2023, there were no outstanding NGL imbalances owed to the Company's operating subsidiaries.

Fair Value Measurements and Inv

Fair Value Measurements and Investments	9 Months Ended
Fair Value Measurements and Investments	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements and Investments	Fair Value Measurements and Investments Financial Assets and Liabilities The methods and assumptions used in estimating the fair value amounts included in the disclosures for financial assets and liabilities are consistent with those disclosed in the Company's 2023 Annual Report on Form 10-K. The Company had equity securities recorded at fair value on a recurring basis in Other Current Assets of $2.5 million a nd $2.3 million as of September 30, 2024, and December 31, 2023, which were considered Level 1 investments. The Company had no liabilities recorded at fair value on a recurring basis as of September 30, 2024, and December 31, 2023. The carrying amounts and estimated fair values of the Company's financial assets and liabilities which were not recorded at fair value on the Condensed Consolidated Balance Sheets as of September 30, 2024, and December 31, 2023, were as follows (in millions): As of September 30, 2024 Estimated Fair Value Financial Assets Carrying Amount Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 255.9 $ 255.9 $ — $ — $ 255.9 Short-term investments 603.1 603.7 — — 603.7 Financial Liabilities Debt, current and long-term $ 3,835.6 (1) $ — $ 3,797.4 $ — $ 3,797.4 (1) The carrying amount of debt excluded a $2.9 million long-term finance lease obligation and $5.1 million of unamortized debt issuance costs. As of December 31, 2023 Estimated Fair Value Financial Assets Carrying Amount Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 20.1 $ 20.1 $ — $ — $ 20.1 Financial Liabilities Long-term debt $ 3,262.4 (1) $ — $ 3,155.3 $ — $ 3,155.3 (1) The carrying amount of long-term debt excluded a $3.6 million long-term finance lease obligation and $4.1 million of unamortized debt issuance costs.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2024
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 was 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 was against Boardwalk GP, and not the Company or its subsidiaries. The Defendants believed that the Trial Court ruling included 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. Oral arguments were held on September 14, 2022, and on December 19, 2022, the Supreme Court reversed the Trial Court's ruling and remanded the case to the Trial Court for further proceedings related to claims not decided by the Trial Court's ruling. Briefing by the parties at the Trial Court on the remanded issues was completed in September 2023. A hearing on the remanded issues was held at the Trial Court in April 2024. In September 2024, the Trial Court ruled in favor of the Defendants on all of the remanded issues. On October 21, 2024, the Plaintiffs appealed the Trial Court's ruling on the remanded issues to the Supreme Court. City of New Orleans Litigation Gulf South Pipeline Company, LLC (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 Fifth Circuit Court of Appeals in a similar case. On August 5, 2021, the Fifth 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 Fifth 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. Discovery has been initiated. Gulf South and Texas Gas Transmission, LLC (Texas Gas) have been named as defendants in several suits in the State of Louisiana that are similar in nature to the City of New Orleans Litigation discussed above. These cases were filed in Louisiana state courts and discovery is ongoing. One of these cases was settled in the second quarter 2024 and it did not have a material impact to the Company's results of operations or equity. Regulatory Cost Recovery Mechanism On May 1, 2024, Gulf South filed with the FERC a regulatory cost recovery mechanism, to be included in Gulf South's tariff, that would allow Gulf South to track and recover, via a surcharge, the costs of complying with certain new environmental regulatory requirements and regulatory requirements imposed by the Pipeline and Hazardous Materials Safety Administration. Gulf South requested that the regulatory cost recovery mechanism have an initial term of five years beginning on November 1, 2024. On October 31, 2024, Gulf South received an order from the FERC rejecting the cost recovery mechanism. 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 September 30, 2024, the commitments were approximately $141.3 million, all of which are expected to be settled within the next twelve months.

Financing

Financing	9 Months Ended
Financing	Sep. 30, 2024
Debt Disclosure [Abstract]
Financing	Financing Notes and Debentures As of September 30, 2024, and December 31, 2023, the Company had principal amounts of notes and debentures outstanding of $3.9 billion and $3.3 billion, with weighted-average interest rates of 4.98% and 4.84%, of which $600.0 million of the outstanding principal amount has been classified as current and is recorded as a component of Current Liabilities . For the nine months ended September 30, 2024, the Company completed the following debt issuance (in millions, except interest rates): Date of Issuing Subsidiary Amount of Purchaser Net Interest Maturity Date Interest February 2024 Boardwalk Pipelines $ 600.0 $ 6.5 $ 593.5 (1) 5.625 % August 1, 2034 February 1 and August 1 (1) The net proceeds of this offering will be used to retire the outstanding $600.0 million aggregate principal amount of Boardwalk Pipelines 4.95% notes due December 2024 at its maturity. 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 September 30, 2024, the Company and its subsidiaries were in compliance with their covenants under the indentures. Revolving Credit Facility As of September 30, 2024, the Company had no outstanding borrowings under its revolving credit facility and had the full borrowing capacity of $1.0 billion available. As of December 31, 2023, outstanding borrowings under the Company's revolving credit facility were $25.0 million, with a weighted-average interest rate of 6.71%. The revolving credit facility has a borrowing capacity of $1.0 billion through May 27, 2027, and a borrowing capacity of $912.2 million from May 28, 2027, to May 26, 2028. The Company and its subsidiaries were in compliance with all covenant requirements under its revolving credit facility as of September 30, 2024.

Employee Benefits

Employee Benefits	9 Months Ended
Employee Benefits	Sep. 30, 2024
Retirement Benefits [Abstract]
Employee Benefits	Employee Benefits Defined Benefit Retirement Plans (Retirement Plans) and Postretirement Benefits Other Than Pension (PBOP) Components of net periodic benefit cost for both the Retirement Plans and PBOP were as follows (in millions): Retirement Plans PBOP For the For the 2024 2023 2024 2023 Service cost $ 0.5 $ 0.5 $ — $ — Interest cost 1.0 1.1 0.3 0.3 Expected return on plan assets (0.8) (0.9) (0.7) (0.6) Amortization of unrecognized net loss 0.1 0.4 — — Settlement charge 0.2 0.1 — — Net periodic benefit cost (credit) $ 1.0 $ 1.2 $ (0.4) $ (0.3) Retirement Plans PBOP For the For the 2024 2023 2024 2023 Service cost $ 1.5 $ 1.5 $ — $ — Interest cost 3.0 3.1 0.9 0.9 Expected return on plan assets (2.8) (2.7) (2.0) (1.8) Amortization of unrecognized net loss 0.5 1.3 — — Settlement charge 0.6 1.1 — — Net periodic benefit cost (credit) $ 2.8 $ 4.3 $ (1.1) $ (0.9) During the nine months ended September 30, 2024, the Company made $2.2 million in contributions to the defined benefit pension plan and expects to fund an additional $0.8 million in the remainder of 2024. 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 $3.5 million and $3.4 million for the three months ended September 30, 2024 and 2023, and $10.7 million and $10.1 million for the nine months ended September 30, 2024 and 2023.

Related Party Transactions

Related Party Transactions	9 Months Ended
Related Party Transactions	Sep. 30, 2024
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Loews provides a variety of corporate services to the Company under service agreements, including risk management, finance and accounting, legal, tax and corporate development services, and charges the Company for allocated overheads. The Company incurred charges related to these services of $1.4 million and $1.0 million for the three months ended September 30, 2024 and 2023, and $4.1 million and $3.2 million for the nine months ended September 30, 2024 and 2023, which were recorded in Administrative and general on the Condensed Consolidated Statements of Income. Total distributions paid to BPHC and Boardwalk GP were $50.0 million and $150.0 million for the three and nine months ended September 30, 2024. No distributions were paid for the three and nine months ended September 30, 2023.

Supplemental Disclosure of Cash

Supplemental Disclosure of Cash Flow Information	9 Months Ended
Supplemental Disclosure of Cash Flow Information	Sep. 30, 2024
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosure of Cash Flow Information	Supplemental Disclosure of Cash Flow Information (in millions): For the 2024 2023 Cash paid during the period for: Interest (net of amount capitalized) $ 120.2 $ 105.4 Non-cash investing activities: Accounts payable and PPE 25.2 57.4 Right-of-use asset obtained in exchange for lease obligations 9.4 1.5 Gas stored underground and PPE — 47.8

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
Basis of Presentation (Policies)	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The accompanying unaudited condensed consolidated financial statements of the Company have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America (U.S.) (GAAP) have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments (consisting of only normal recurring accruals) necessary to present fairly the Company's financial position as of September 30, 2024, and December 31, 2023, its results of operations, comprehensive income and changes in partners' capital for the three and nine months ended September 30, 2024 and 2023, and its changes in cash flows for the nine months ended September 30, 2024 and 2023, in each case in accordance with GAAP. Reference is made to the Notes to the Consolidated Financial Statements in the Company's Annual Report on Form 10-K for the year ended December 31, 2023 (2023 Annual Report on Form 10-K), which should be read in conjunction with these unaudited condensed consolidated financial statements. The accounting policies described in Note 2 of Part II, Item 8. of the Company's 2023 Annual Report on Form 10-K are the same policies that were used in preparing the accompanying unaudited condensed consolidated financial statements. Results of operations for interim periods may not necessarily be indicative of results for the full year.
Short-Term Investment	Short-Term Investment Accounting Policy The Company has invested in short-term investments that have been classified as held-to-maturity as the Company has the intent and the ability to hold the short-term investments until they mature. As of September 30, 2024, the Company had recorded $603.1 million of U.S. treasury bills on its Condensed Consolidated Balance Sheets, maturing in December 2024, at amortized cost. The carrying amount of the U.S. treasury bills was adjusted for the accretion of discounts over the remaining life of the investment. Income related to the U.S. treasury bills was recorded in Interest Income

Gas and Liquids Stored Underg_2

Gas and Liquids Stored Underground and Gas and NGLs Receivables and Payables (Policies)	9 Months Ended
	Sep. 30, 2024
Oil and Gas, Gas-Balancing Arrangement [Abstract]
Gas and liquids stored underground and gas and NGLs receivables and payables	The operating subsidiaries of the Company provide storage services whereby they store natural gas or NGLs on behalf of customers and also periodically hold customer gas under parking and lending (PAL) services. Since the customers retain title to the gas or NGLs held by the Company in providing these services, the Company does not record the related gas or NGLs on its Condensed Consolidated Balance Sheets.

Acquisition (Tables)

Acquisition (Tables)	9 Months Ended
Acquisition (Tables)	Sep. 30, 2024
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Pro Forma Information	The following unaudited pro forma results of operations of the Company are presented as if the acquisition occurred on January 1, 2023. Such results are not necessarily indicative of future results. These pro forma results also do not reflect any cost savings, operating synergies or revenue enhancements that the Company may achieve or the costs necessary to achieve those objectives (in millions): Pro Forma For the For the Operating revenues $ 497.9 $ 1,453.8 Net income 76.2 274.6

Revenues (Tables)

Revenues (Tables)	9 Months Ended
Revenues (Tables)	Sep. 30, 2024
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following table presents the Company's revenues disaggregated by type of service (in millions): For the For the 2024 2023 2024 2023 Revenues from Contracts with Customers Firm Service (1)(2) $ 413.3 $ 330.4 $ 1,258.3 $ 1,030.3 Interruptible Service 15.0 13.0 47.0 41.1 Other revenues (2) 34.9 3.6 125.9 11.5 Total Revenues from Contracts with Customers 463.2 347.0 1,431.2 1,082.9 Other operating revenues (2)(3) 10.3 8.7 30.3 25.8 Total Operating Revenues $ 473.5 $ 355.7 $ 1,461.5 $ 1,108.7 (1) Revenues earned from contracts with minimum volume commitments (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. (2) For the three and nine months ended September 30, 2024, revenues attributable to Bayou Ethane were $53.9 million and $150.0 million included in firm service from product sales earned from contracts with MVCs; $20.6 million and $91.4 million included in other revenues from product sales earned from contracts with no MVCs; and $1.5 million and $3.8 million included in other operating revenues. (3) 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 nine months ended September 30, 2024, were as follows (in millions): Contract Liabilities Balance as of December 31, 2023 (1) $ 21.4 Revenues recognized that were included in the contract liability (3.5) Increases due to cash received, excluding amounts recognized as 1.9 Balance as of September 30, 2024 (1) $ 19.8 (1) As of September 30, 2024, and December 31, 2023, $3.3 million and $3.5 million were recorded in Other Current Liabilities (current portion), and $16.5 million and $17.9 million were recorded in Other Liabilities (noncurrent portion). Significant changes in the contract liability balances during the nine months ended September 30, 2023, were as follows (in millions): Contract Liabilities Balance as of December 31, 2022 (1) $ 23.0 Revenues recognized that were included in the contract liability (3.0) Increases due to cash received, excluding amounts recognized as 1.6 Other 0.6 Balance as of September 30, 2023 (1) $ 22.2 (1) As of September 30, 2023, and December 31, 2022, $3.7 million and $3.6 million were recorded in Other Current Liabilities (current portion), and $18.5 million and $19.4 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 September 30, 2024. 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, or at a point in time as guaranteed minimum fees associated with the performance obligation are satisfied under certain ethane supply contracts. For the Company's customers that are charged maximum tariff rates related to its Federal Energy Regulatory Commission (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 variable nature of such services; (b) unsatisfied performance obligations from the ethane commodity indexed portion of ethane supply contracts because of the variable nature of ethane prices, and (c) consideration in contracts that is recognized in revenue as invoiced, such as for interruptible services. 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 2024 (1) 2025 Thereafter Total Estimated revenues from contracts with customers from unsatisfied performance obligations as of September 30, 2024 $ 397.0 $ 1,449.0 $ 8,962.5 $ 10,808.5 Operating revenues which are fixed and 7.0 27.5 163.0 197.5 Total projected operating revenues under committed firm agreements as of September 30, 2024 (2) $ 404.0 $ 1,476.5 $ 9,125.5 $ 11,006.0 (1) The 2024 period is for the remaining three months ending December 31, 2024. For the nine months ended September 30, 2024, the Company recognized $1,084.5 million of fixed fee revenues for the fulfillment of performance obligations. (2) In March 2024, the Company executed a 108-year firm storage agreement with a customer. The estimated annual revenue from this contract is $3.1 million, with $331.6 million of unsatisfied performance obligations included in the “Thereafter” column. Per the tariff provisions, this customer was required to provide 90 days of collateral and the Company can suspend services due to non-payment.

Fair Value Measurements and I_2

Fair Value Measurements and Investments (Tables)	9 Months Ended
Fair Value Measurements and Investments (Tables)	Sep. 30, 2024
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 Condensed Consolidated Balance Sheets as of September 30, 2024, and December 31, 2023, were as follows (in millions): As of September 30, 2024 Estimated Fair Value Financial Assets Carrying Amount Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 255.9 $ 255.9 $ — $ — $ 255.9 Short-term investments 603.1 603.7 — — 603.7 Financial Liabilities Debt, current and long-term $ 3,835.6 (1) $ — $ 3,797.4 $ — $ 3,797.4 (1) The carrying amount of debt excluded a $2.9 million long-term finance lease obligation and $5.1 million of unamortized debt issuance costs. As of December 31, 2023 Estimated Fair Value Financial Assets Carrying Amount Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 20.1 $ 20.1 $ — $ — $ 20.1 Financial Liabilities Long-term debt $ 3,262.4 (1) $ — $ 3,155.3 $ — $ 3,155.3 (1) The carrying amount of long-term debt excluded a $3.6 million long-term finance lease obligation and $4.1 million of unamortized debt issuance costs.

Financing (Tables)

Financing (Tables)	9 Months Ended
Financing (Tables)	Sep. 30, 2024
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	For the nine months ended September 30, 2024, the Company completed the following debt issuance (in millions, except interest rates): Date of Issuing Subsidiary Amount of Purchaser Net Interest Maturity Date Interest February 2024 Boardwalk Pipelines $ 600.0 $ 6.5 $ 593.5 (1) 5.625 % August 1, 2034 February 1 and August 1 (1)

Employee Benefits (Tables)

Employee Benefits (Tables)	3 Months Ended	9 Months Ended
Employee Benefits (Tables)	Sep. 30, 2024	Sep. 30, 2024
Retirement Benefits [Abstract]
Schedule of Net Benefit Costs	Components of net periodic benefit cost for both the Retirement Plans and PBOP were as follows (in millions): Retirement Plans PBOP For the For the 2024 2023 2024 2023 Service cost $ 0.5 $ 0.5 $ — $ — Interest cost 1.0 1.1 0.3 0.3 Expected return on plan assets (0.8) (0.9) (0.7) (0.6) Amortization of unrecognized net loss 0.1 0.4 — — Settlement charge 0.2 0.1 — — Net periodic benefit cost (credit) $ 1.0 $ 1.2 $ (0.4) $ (0.3)	Retirement Plans PBOP For the For the 2024 2023 2024 2023 Service cost $ 1.5 $ 1.5 $ — $ — Interest cost 3.0 3.1 0.9 0.9 Expected return on plan assets (2.8) (2.7) (2.0) (1.8) Amortization of unrecognized net loss 0.5 1.3 — — Settlement charge 0.6 1.1 — — Net periodic benefit cost (credit) $ 2.8 $ 4.3 $ (1.1) $ (0.9)

Supplemental Disclosure of Ca_2

Supplemental Disclosure of Cash Flow Information (Tables)	9 Months Ended
Supplemental Disclosure of Cash Flow Information (Tables)	Sep. 30, 2024
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosure of Cash Flow Information	Supplemental Disclosure of Cash Flow Information (in millions): For the 2024 2023 Cash paid during the period for: Interest (net of amount capitalized) $ 120.2 $ 105.4 Non-cash investing activities: Accounts payable and PPE 25.2 57.4 Right-of-use asset obtained in exchange for lease obligations 9.4 1.5 Gas stored underground and PPE — 47.8

Basis of Presentation (Details)

Basis of Presentation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Basis of Presentation (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenue Recognition [Line Items]
Product sales, increase	$ 84.3	$ 0	$ 263.1	$ 0.8
Other revenue, decrease	$ (20)	$ (16.5)	$ (57.6)	(51.5)
Revision of Prior Period, Reclassification, Adjustment
Revenue Recognition [Line Items]
Product sales, increase				0.8
Other revenue, decrease				$ (0.8)
Boardwalk Pipelines Holding Corp. (BPHC) \| Boardwalk Pipeline Partners, LP
Noncontrolling Interest [Line Items]
Ownership percentage	100%		100%

Basis of Presentation - Investm

Basis of Presentation - Investments (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Short-term investments	$ 603.1	$ 0
Short-term investments, unrecognized gain	$ 0.6

Acquisition - Narrative (Detail

Acquisition - Narrative (Details) $ in Millions	Sep. 29, 2023 USD ($)
Bayou Ethane \| Boardwalk Resources Company, LLC
Statement [Line Items]
Payments to acquire business	$ 355

Acquisition - Pro Forma Financi

Acquisition - Pro Forma Financial Information (Details) - Bayou Ethane - Boardwalk Resources Company, LLC - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Operating revenues	$ 497.9	$ 1,453.8
Net income	$ 76.2	$ 274.6

Revenues - Narrative (Details)

Revenues - Narrative (Details) $ in Millions	9 Months Ended
Revenues - Narrative (Details) $ in Millions	Sep. 30, 2024 USD ($) segments	Dec. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Revenue from Contract with Customer [Abstract]
Number of reportable segments \| segments	1
Receivables from contracts with customers	$ 161.2	$ 204.6
Contract assets from contracts with customers	10.8	6.2
Contract liabilities from contracts with customers	$ 19.8	$ 21.4	$ 22.2	$ 23

Revenues - Disaggregation of Re

Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	$ 463.2	$ 347	$ 1,431.2	$ 1,082.9
Other operating revenues	30.3	8.7	10.3	25.8
Total operating revenues	473.5	355.7	1,461.5	1,108.7
Firm Service
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,258.3	330.4	413.3	1,030.3
Firm Service \| Bayou Ethane \| Boardwalk Resources Company, LLC
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	150		53.9
Interruptible Service
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	47	13	15	41.1
Interruptible Service \| Bayou Ethane \| Boardwalk Resources Company, LLC
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	91.4		20.6
Other revenues
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	125.9	$ 3.6	34.9	$ 11.5
Other revenues \| Bayou Ethane \| Boardwalk Resources Company, LLC
Disaggregation of Revenue [Line Items]
Other operating revenues	$ 3.8		$ 1.5

Revenues - Contract Liability B

Revenues - Contract Liability Balance Activity (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Contract With Customer, Liability [Roll Forward]
Beginning Balance	$ 21.4	$ 23
Revenues recognized that were included in the contract liability balances at the beginning of the period	3.5	(3)
Increases due to cash received, excluding amounts recognized as revenues during the period	1.9	1.6
Other		0.6
Ending Balance	19.8	22.2
Contract with customer, liability, current	3.3	3.7	$ 3.5	$ 3.6
Contract with customer, liability, noncurrent	$ 16.5	$ 18.5	$ 17.9	$ 19.4

Revenues - Performance Obligati

Revenues - Performance Obligations (Details) $ in Millions	9 Months Ended
Revenues - Performance Obligations (Details) $ in Millions	Sep. 30, 2024 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated revenues from contracts with customers from unsatisfied performance obligations as of September 30, 2024	$ 10,808.5
Operating revenues which are fixed and determinable (operating leases)	197.5
Total projected operating revenues under committed firm agreements as of September 30, 2024 (2)	11,006
Fixed fee revenues recognized	$ 1,084.5
Firm storage, term of contract for particular customer	108 years
Estimated annual revenue from particular customer	$ 3.1
Revenue remaining performance obligation for particular customer	$ 331.6
Days of collateral required for particular customer	90 days
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, period	9 months
Estimated revenues from contracts with customers from unsatisfied performance obligations as of September 30, 2024	$ 397
Operating revenues which are fixed and determinable (operating leases)	7
Total projected operating revenues under committed firm agreements as of September 30, 2024 (2)	$ 404
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, period	1 year
Estimated revenues from contracts with customers from unsatisfied performance obligations as of September 30, 2024	$ 1,449
Operating revenues which are fixed and determinable (operating leases)	27.5
Total projected operating revenues under committed firm agreements as of September 30, 2024 (2)	$ 1,476.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, period	48 years
Estimated revenues from contracts with customers from unsatisfied performance obligations as of September 30, 2024	$ 8,962.5
Operating revenues which are fixed and determinable (operating leases)	163
Total projected operating revenues under committed firm agreements as of September 30, 2024 (2)	$ 9,125.5

Gas and Liquids Stored Underg_3

Gas and Liquids Stored Underground and Gas and NGLs Receivables and Payables (Details) MMBTU in Millions, $ in Millions	Sep. 30, 2024 USD ($) $ / lb $ / MMBTU MMBTU MMBbls pounds	Dec. 31, 2023 USD ($) $ / MMBTU MMBTU MMBbls pounds
Oil and Gas, Gas-Balancing Arrangement [Abstract]
Gas balancing measurement (in TBtu) \| MMBTU	6.7	11.2
Average market price of gas assumed (in dollars per MMBTU) \| $ / MMBTU	2.17	2.33
Gas imbalance to subsidiaries asset liability	$ 14.5	$ 26.1
Ethylene loaned volume (in pounds) \| pounds	34,000,000	0
Average market price of ethylene assumed (in dollars per pound) \| $ / lb	0.21
Ethylene loaned balance due to operating subsidiaries (asset)	$ 7.1
Natural gas liquids balancing measurement (in MMBbls) \| MMBbls	0	0

Fair Value Measures and Investm

Fair Value Measures and Investments - Narrative (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities, fair value, recurring basis	$ 0	$ 0
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, fair value, recurring basis	$ 2.5	$ 2.3

Fair Value Measurements and I_3

Fair Value Measurements and Investments - Financial Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Financial Assets
Cash and cash equivalents	$ 255.9	$ 20.1
Short-term investments fair value	603.7
Financial Liabilities
Debt, current and long-term	3,797.4	3,155.3
Long-term finance lease obligation	2.9	3.6
Unsecured Debt
Financial Liabilities
Unamortized debt issuance costs	5.1	4.1
Carrying Amount
Financial Assets
Cash and cash equivalents	255.9	20.1
Short-term investments carrying amount	603.1
Financial Liabilities
Debt, current and long-term	3,835.6	3,262.4
Estimated Fair Value \| Level 1
Financial Assets
Cash and cash equivalents	255.9	20.1
Short-term investments fair value	603.7
Financial Liabilities
Debt, current and long-term	0	0
Estimated Fair Value \| Level 2
Financial Assets
Cash and cash equivalents	0	0
Short-term investments fair value	0
Financial Liabilities
Debt, current and long-term	3,797.4	3,155.3
Estimated Fair Value \| Level 3
Financial Assets
Cash and cash equivalents	0	0
Short-term investments fair value	0
Financial Liabilities
Debt, current and long-term	$ 0	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Legal Proceedings and Settlements (Details) $ in Millions	Nov. 12, 2021 USD ($)	Aug. 05, 2021 case
City Of New Orleans Litigation \| Pending Litigation
Loss Contingencies [Line Items]
Number of cases \| case		2
Boardwalk GP, LP
Loss Contingencies [Line Items]
Legal damages awarded to other party (approximately)	$ 690
Pre-judgment interest awarded to other party (approximately)	$ 166

Commitments and Contingencies_2

Commitments and Contingencies - Commitments for Construction (Details) $ in Millions	Sep. 30, 2024 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Purchase commitment, expected to be settled in the next twelve months	$ 141.3

Financing (Details)

Financing (Details) - USD ($)	Feb. 29, 2024	Sep. 30, 2024	Dec. 31, 2023
Unsecured Debt
Debt Instrument [Line Items]
Weighted-average interest rates		4.98%	4.84%
Unsecured Debt \| Boardwalk Pipelines 4.95% Notes Due 2024
Debt Instrument [Line Items]
Current portion of long-term debt		$ 600,000,000
Debt, interest rate		4.95%
Unsecured Debt \| Boardwalk Pipelines 5.625% Notes Due 2034
Debt Instrument [Line Items]
Amount of issuance	$ 600,000,000
Purchaser discounts and expenses	6,500,000
Net proceeds	$ 593,500,000
Debt, interest rate	5.625%
Unsecured Debt \| Total Notes And Debentures
Debt Instrument [Line Items]
Total notes and debentures		$ 3,900,000,000	$ 3,300,000,000
Line of Credit
Debt Instrument [Line Items]
Weighted-average interest rates			6.71%
Line of Credit Facility [Abstract]
Available borrowing capacity		1,000,000,000
Line of credit, outstanding borrowings		0	$ 25,000,000
Line of Credit \| Amendment No. 3 Credit Agreement - 2021
Line of Credit Facility [Abstract]
Maximum borrowing capacity		1,000,000,000
Line of Credit \| Amendment No. 5 Credit Agreement - 2023
Line of Credit Facility [Abstract]
Maximum borrowing capacity		$ 912,200,000

Employee Benefits - Narrative (

Employee Benefits - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost	$ 3.5	$ 3.4	$ 10.7	$ 10.1
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contribution to defined benefit pension plan			2.2
Expected future contributions	$ 0.8		$ 0.8

Employee Benefits - Components

Employee Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Retirement Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 0.5	$ 0.5	$ 1.5	$ 1.5
Interest cost	1	1.1	3	3.1
Expected return on plan assets	(0.8)	(0.9)	(2.8)	(2.7)
Amortization of unrecognized net loss	0.1	0.4	0.5	1.3
Settlement charge	0.2	0.1	0.6	1.1
Net periodic benefit cost (credit)	1	1.2	2.8	4.3
PBOP
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	0	0	0	0
Interest cost	0.3	0.3	0.9	0.9
Expected return on plan assets	(0.7)	(0.6)	(2)	(1.8)
Amortization of unrecognized net loss	0	0	0	0
Settlement charge	0	0	0	0
Net periodic benefit cost (credit)	$ (0.4)	$ (0.3)	$ (1.1)	$ (0.9)

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	3 Months Ended		9 Months Ended
Related Party Transactions (Details) - USD ($)	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Related Party Transaction [Line Items]
Administrative and general	$ 45,600,000	$ 44,200,000	$ 137,800,000	$ 126,700,000
Cash dividends paid to parent company			150,000,000	0
Parent Company
Related Party Transaction [Line Items]
Cash dividends paid to parent company	50,000,000	0	150,000,000	0
Affiliates
Related Party Transaction [Line Items]
Administrative and general	$ 1,400,000	$ 1,000,000	$ 4,100,000	$ 3,200,000

Supplemental Disclosure of Ca_3

Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash paid during the period for:
Interest (net of amount capitalized)	$ 120.2	$ 105.4
Non-cash investing activities:
Accounts payable and PPE	25.2	57.4
Right-of-use asset obtained in exchange for lease obligations	9.4	1.5
Gas stored underground and PPE	$ 0	$ 47.8