Plug Power (PLUG) 10-Q5 Aug 212021 Q2 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2021	Aug. 02, 2021
Document and Entity Information:
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 2021
Entity File Number	1-34392
Entity Registrant Name	Plug Power Inc
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	22-3672377
Entity Address, Address Line One	968 ALBANY SHAKER ROAD
Entity Address, City or Town	LATHAM
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	12110
City Area Code	518
Local Phone Number	782-7700
Title of 12(b) Security	Common Stock, par value $.01 per share
Trading Symbol	PLUG
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		574,355,448
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2021
Entity Central Index Key	0001093691
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 3,160,170	$ 1,312,404
Restricted cash	81,460	64,041
Available-for-sale securities, at fair value (amortized cost $1,244,618 and allowance for credit losses of $0 at June 30, 2021)	1,242,721
Equity securities	120,302
Accounts receivable	91,359	43,041
Inventory	209,820	139,386
Prepaid expenses and other current assets	60,579	44,324
Total current assets	4,966,411	1,603,196
Restricted cash	347,933	257,839
Property, plant, and equipment, net	110,475	74,549
Right of use assets related to finance leases, net	16,926	5,724
Right of use assets related to operating leases, net	145,803	117,016
Equipment related to power purchase agreements and fuel delivered to customers, net	78,918	75,807
Goodwill	72,083	72,387
Intangible assets, net	38,052	39,251
Other assets	12,225	5,513
Total assets	5,788,826	2,251,282
Current liabilities:
Accounts payable	70,027	50,198
Accrued expenses	35,405	46,083
Deferred revenue	27,004	23,275
Operating lease liabilities	19,915	14,314
Finance lease liabilities	2,728	903
Finance obligations	33,846	32,717
Current portion of long-term debt	30,403	25,389
Other current liabilities	31,750	29,487
Total current liabilities	251,078	222,366
Deferred revenue	45,272	32,944
Operating lease liabilities	122,203	99,624
Finance lease liabilities	12,380	4,493
Finance obligations	161,959	148,836
Convertible senior notes, net	192,011	85,640
Long-term debt	130,081	150,013
Other liabilities	42,973	40,447
Total liabilities	957,957	784,363
Stockholders' equity:
Common stock, $0.01 par value per share; 750,000,000 shares authorized; Issued (including shares in treasury): 586,848,225 at June 30, 2021 and 473,977,469 at December 31, 2020	5,868	4,740
Additional paid-in capital	6,962,720	3,446,650
Accumulated other comprehensive (loss) income	34	2,451
Accumulated deficit	(2,097,319)	(1,946,488)
Less common stock in treasury: 15,926,068 at both June 30, 2021 and December 31, 2020	(40,434)	(40,434)
Total stockholders' equity	4,830,869	1,466,919
Total liabilities and stockholders' equity	$ 5,788,826	$ 2,251,282

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Condensed Consolidated Balance Sheets
Debt Securities, Available-for-sale, Amortized Cost, Current	$ 1,244,618
Debt Securities, Available-for-sale, Allowance for Credit Loss, Current	$ 0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	586,848,225	473,977,469
Common stock in treasury, shares	15,926,068	15,926,068

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net revenue:
Net revenue	$ 124,557	$ 67,995	$ 196,515	$ 108,814
Cost of revenue:
Total cost of revenue	164,855	68,010	248,984	118,532
Gross loss	(40,298)	(15)	(52,469)	(9,718)
Operating expenses:
Research and development	11,247	4,873	20,989	9,647
Selling, general and administrative	38,652	21,644	64,231	32,753
Change in fair value of contingent consideration	(560)		230
Total operating expenses	49,339	26,517	85,450	42,400
Operating loss	(89,637)	(26,532)	(137,919)	(52,118)
Interest	(10,268)	(13,368)	(22,534)	(25,157)
Other expense, net	(70)	(94)	(268)	(151)
Realized gain on investments, net	18		18
Change in fair value of equity securities	323		323
Gain on extinguishment of debt		13,222		13,222
Loss before income taxes	(99,634)	(26,772)	(160,380)	(64,204)
Income tax benefit	0	17,371	0	17,371
Net loss attributable to the Company	(99,634)	(9,401)	(160,380)	(46,833)
Preferred stock dividends declared		(13)		(26)
Net loss attributable to common stockholders	$ (99,634)	$ (9,414)	$ (160,380)	$ (46,859)
Net loss per share:
Basic and diluted	$ (0.18)	$ (0.03)	$ (0.30)	$ (0.15)
Weighted average number of common stock outstanding	567,033,722	316,645,050	540,394,003	310,918,626
Sales of fuel cell systems and related infrastructure
Net revenue:
Net revenue	$ 99,278	$ 47,746	$ 146,050	$ 68,214
Cost of revenue:
Total cost of revenue	79,913	33,888	108,887	47,862
Services performed on fuel cell systems and related infrastructure
Net revenue:
Net revenue	5,675	6,236	11,720	12,757
Cost of revenue:
Total cost of revenue	15,475	7,773	28,561	18,120
Provision for loss contracts related to service
Cost of revenue:
Total cost of revenue	6,694	706	8,179	801
Power Purchase Agreements
Net revenue:
Net revenue	8,361	6,579	16,187	13,000
Cost of revenue:
Total cost of revenue	22,234	14,504	40,577	29,275
Fuel delivered to customers
Net revenue:
Net revenue	11,121	7,372	22,248	14,705
Cost of revenue:
Total cost of revenue	40,331	11,076	62,474	22,330
Other
Net revenue:
Net revenue	122	62	310	138
Cost of revenue:
Total cost of revenue	$ 208	$ 63	$ 306	$ 144

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Condensed Consolidated Statements of Comprehensive Loss
Net loss attributable to the Company	$ (99,634)	$ (9,401)	$ (160,380)	$ (46,833)
Foreign currency translation (loss) gain	581	107	(542)	(129)
Change in net unrealized loss on available-for-sale securities	(1,967)		(1,875)
Comprehensive loss attributable to the Company	(101,020)	(9,294)	(162,797)	(46,962)
Preferred stock dividends declared		(13)		(26)
Comprehensive loss attributable to common stockholders	$ (101,020)	$ (9,307)	$ (162,797)	$ (46,988)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock3.75% Convertible Senior Notes	Common Stock5.5% Convertible Senior Notes	Common StockPrivate placement	Common Stock	Additional Paid-in-Capital3.75% Convertible Senior Notes	Additional Paid-in-Capital5.5% Convertible Senior Notes	Additional Paid-in-CapitalPrivate placement	Additional Paid-in-Capital	Accumulated Other Comprehensive Income	Treasury Stock	Accumulated Deficit	3.75% Convertible Senior Notes	5.5% Convertible Senior Notes	Private placement	Total
Balance at Dec. 31, 2019				$ 3,186				$ 1,506,953	$ 1,288	$ (31,216)	$ (1,350,307)				$ 129,904
Balance (in shares) at Dec. 31, 2019				318,637,560						15,259,045
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company											(46,833)				(46,833)
Other comprehensive loss									(129)						(129)
Stock-based compensation				$ 6				6,325		$ (143)					6,188
Stock-based compensation (in shares)				586,558						33,371
Stock dividend								20			(20)
Stock dividend (in shares)				5,156
Issuance of common stock, net								(269)							(269)
Stock option exercises				$ 69				15,729							15,798
Stock option exercises (in shares)				6,905,936						175
Equity component of convertible senior notes, net of issuance costs and income tax (benefit) expense								115,952							115,952
Purchase of capped calls								(16,253)							(16,253)
Termination of capped calls								24,158							24,158
Provision for common stock warrants								7,983							7,983
Accretion of discount, preferred stock								(29)							(29)
Conversion of preferred stock				$ 30				1,148							1,178
Conversion of preferred stock (in shares)				2,998,526
Repurchase of 5.5% Convertible Senior Notes, net of income tax benefit				$ 94				(52,855)							(52,761)
Repurchase of 5.5% Convertible Senior Notes, net of income tax benefit (in shares)				9,409,591
Shares issued for acquisitions				$ 97				49,576							49,673
Shares issued for acquisitions (in shares)				9,658,465
Balance at Jun. 30, 2020				$ 3,482				1,658,438	1,159	$ (31,359)	(1,397,160)				234,560
Balance (in shares) at Jun. 30, 2020				348,201,792						15,292,591
Balance (ASU 2020-06) at Dec. 31, 2020								(130,185)			9,549				(120,636)
Balance at Dec. 31, 2020				$ 4,740				3,446,650	2,451	$ (40,434)	(1,946,488)				$ 1,466,919
Balance (in shares) at Dec. 31, 2020				473,977,469						15,926,068					473,977,469
Increase (Decrease) in Stockholders' Equity
Net loss attributable to the Company											(160,380)				$ (160,380)
Other comprehensive loss									(2,417)						(2,417)
Stock-based compensation								20,815							20,815
Stock-based compensation (in shares)				15,166
Issuance of common stock, net			$ 549	$ 322			$ 1,564,088	2,022,866						$ 1,564,637	2,023,188
Issuance of common stock, net (in shares)			54,966,188	32,200,000
Stock option exercises				$ 18				4,687							4,705
Stock option exercises (in shares)				1,760,450
Exercise of warrants				$ 208				15,242							15,450
Exercise of warrants (in shares)				20,843,108
Provision for common stock warrants								3,243							3,243
Conversion of Convertible Senior Notes	$ 30	$ 1			$ 15,155	$ 159						$ 15,185	$ 160
Conversion of Convertible Senior Notes (in shares)	3,016,036	69,808
Balance at Jun. 30, 2021				$ 5,868				$ 6,962,720	$ 34	$ (40,434)	$ (2,097,319)				$ 4,830,869
Balance (in shares) at Jun. 30, 2021				586,848,225						15,926,068					586,848,225

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders' Equity (Parenthetical)	Jun. 30, 2021	Mar. 31, 2021	Jan. 31, 2021	Jan. 07, 2021	Jan. 01, 2021	Dec. 31, 2020	Jun. 30, 2020	May 31, 2020	May 29, 2020	May 18, 2020	Mar. 31, 2018
Interest rate (as a percent)					3.75%
5.5% Convertible Senior Notes
Interest rate (as a percent)	5.50%		5.50%	5.50%		5.50%	5.50%	5.50%		5.50%	5.50%
3.75% Convertible Senior Notes
Interest rate (as a percent)	3.75%	3.75%						3.75%	3.75%	3.75%

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Operating Activities
Net loss attributable to the Company	$ (99,634)	$ (9,401)	$ (160,380)	$ (46,833)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of long-lived assets			9,725	6,069
Amortization of intangible assets	400	200	730	398
Stock-based compensation			20,815	6,188
Gain on extinguishment of debt		(13,222)		(13,222)
Amortization of debt issuance costs and discount on convertible senior notes			1,726	6,528
Provision for common stock warrants			3,452	7,983
Income tax benefit	0	(17,371)	0	(17,371)
Loss on service contracts			4,399	277
Fair value adjustment to contingent consideration			(230)
Net realized gain on investments	(18)		(18)
Lease origination costs			(4,553)
Change in fair value for equity securities	(323)		(323)
Changes in operating assets and liabilities that provide (use) cash:
Accounts receivable			(48,318)	(18,333)
Inventory			(70,588)	(37,983)
Prepaid expenses, and other assets			(22,967)	(11,887)
Accounts payable, accrued expenses, and other liabilities			4,047	3,903
Deferred revenue			15,848	2,392
Net cash used in operating activities			(246,635)	(111,891)
Investing Activities
Purchases of property, plant and equipment			(33,062)	(5,009)
Purchases of equipment related to Power Purchase Agreements and equipment related to fuel delivered to customers			(7,598)	(6,256)
Purchase of available-for-sale securities			(1,504,891)
Proceeds from sales and maturities of available-for-sale securities			260,313
Purchase of equity securities			(119,979)
Net cash paid for acquisition				(45,286)
Net cash used in investing activities			(1,405,217)	(56,551)
Financing Activities
Proceeds from exercise of warrants, net of transaction costs			15,450
Proceeds from public and private offerings, net of transaction costs			3,587,825	(269)
Proceeds from exercise of stock options			4,705	15,798
Proceeds from issuance of convertible senior notes, net				205,100
Repurchase of convertible senior notes				(90,238)
Purchase of capped calls and common stock forward				(16,253)
Proceeds from termination of capped calls				24,158
Principal payments on long-term debt			(15,564)	(21,626)
Proceeds from long-term debt, net				49,000
Repayments of finance obligations and finance lease			(17,281)	(11,129)
Proceeds from finance obligations			32,159	27,678
Net cash provided by financing activities			3,607,294	182,219
Effect of exchange rate changes on cash			(163)	(24)
Increase in cash, cash equivalents and restricted cash			1,955,279	13,753
Cash, cash equivalents, and restricted cash beginning of period			1,634,284	369,500	$ 369,500
Cash, cash equivalents, and restricted cash end of period	$ 3,589,563	$ 383,253	3,589,563	383,253	$ 1,634,284
Supplemental disclosure of cash flow information
Cash paid for interest			11,261	9,466
Summary of non-cash activity
Recognition of right of use asset - finance leases			11,286
Recognition of right of use asset - operating leases			39,271	6,836
Conversion of preferred stock to common stock				$ 441
Conversion of convertible senior notes to common stock			15,345
Changes in accounts pyable related to accrued purchases of property, plant and equipment			$ 6,124

Nature of Operations

Nature of Operations	6 Months Ended
Nature of Operations	Jun. 30, 2021
Nature of Operations
Nature of Operations	1. Nature of Operations Plug Power is facilitating the paradigm shift to an increasingly electrified world by innovating cutting-edge hydrogen and fuel cell solutions. In our core business, we provide and continue to develop commercially viable hydrogen and fuel cell product solutions to replace lead-acid batteries in electric material handling vehicles and industrial trucks for some of the world’s largest retail-distribution and manufacturing businesses. We are focusing our efforts on industrial mobility applications, including electric forklifts and electric industrial vehicles, at multi-shift high volume manufacturing and high throughput distribution sites where we believe our products and services provide a unique combination of productivity, flexibility, and environmental benefits. Additionally, we manufacture and sell fuel cell products to replace batteries and diesel generators in stationary backup power applications. These products have proven valuable with telecommunications, transportation, and utility customers as robust, reliable, and sustainable power solutions. Our current products and services include: GenDrive: GenDrive is our hydrogen fueled Proton Exchange Membrane (“PEM”) fuel cell system providing power to material handling electric vehicles, including class 1, 2, 3 and 6 electric forklifts, Automated Guided Vehicles (“AGVs”) and ground support equipment; GenFuel: GenFuel is our liquid hydrogen fueling delivery, generation, storage, and dispensing system; GenCare: GenCare is our ongoing ‘internet of things’-based maintenance and on-site service program for GenDrive fuel cell systems, GenSure fuel cell systems, GenFuel hydrogen storage and dispensing products and ProGen fuel cell engines; GenSure: GenSure is our stationary fuel cell solution providing scalable, modular PEM fuel cell power to support the backup and grid-support power requirements of the telecommunications, transportation, and utility sectors; GenSure High Power Fuel Cell Platform will support large scale stationary power and data center markets; GenKey: GenKey is our vertically integrated “turn-key” solution combining either GenDrive or GenSure fuel cell power with GenFuel fuel and GenCare aftermarket service, offering complete simplicity to customers transitioning to fuel cell power; ProGen: ProGen is our fuel cell stack and engine technology currently used globally in mobility and stationary fuel cell systems, and as engines in electric delivery vans. This includes the Plug Power membrane electrode assembly (“MEA”), a critical component of the fuel cell stack used in zero-emission fuel cell electric vehicle engines; and GenFuel Electrolyzers: GenFuel electrolyzers are modular, scalable hydrogen generators optimized for clean hydrogen production. We provide our products worldwide through our direct product sales force, and by leveraging relationships with original equipment manufacturers (“OEMs”) and their dealer networks. Plug Power is targeting Asia and Europe for expansion in adoption. Europe has rolled out ambitious targets for the hydrogen economy and Plug Power is executing on its strategy to become one of the European leaders. This includes a targeted account strategy for material handling as well as securing strategic partnerships with European OEMs, energy companies, utility leaders and accelerating our electrolyzer business. We manufacture our commercially viable products in Latham, New York, Rochester, New York and Spokane, Washington and support liquid hydrogen generation and logistics in Charleston, Tennessee. Our wholly-owned subsidiary, Plug Power France, has created a joint venture with Renault SAS (“Renault”) named HyVia, a French société par actions simplifiée (“HyVia”). HyVia plans to manufacture and sell fuel cell powered electric light commercial vehicles (“FCELCVs”) and to supply hydrogen fuel and fueling stations to support the FCE-LCV market, in each case primarily in Europe. HyVia is owned 50% by Plug Power France and 50% by Renault.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
Summary of Significant Accounting Policies	Jun. 30, 2021
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Restatement As previously disclosed in the Explanatory Note to the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2020 (the “2020 10-K”), the Company restated its previously issued audited consolidated financial statements as of and for the years ended December 31, 2019 and 2018 and its unaudited interim condensed consolidated financial statements as of and for each of the quarterly periods ended March 31, 2020 and 2019, June 30, 2020 and 2019, September 30, 2020 and 2019 and December 31, 2019. Previously filed annual reports on Form 10-K and quarterly reports on Form 10-Q for the periods affected by the restatement have not been amended. Accordingly, investors should not rely upon the Company’s previously released financial statements for these periods and any earnings releases or other communications relating to these periods, and, for these periods, investors should rely solely on the financial statements and other financial data for the relevant periods included in the 2020 10-K. Commencing with our quarterly report on Form 10-Q for the quarterly period ended March 31, 2021, we are including in our quarterly reports for fiscal 2021 restated results for the corresponding interim periods of fiscal 2020. Principles of Consolidation The unaudited interim condensed consolidated financial statements include the financial statements of the Company and its wholly-owned subsidiaries. Intercompany balances and transactions have been eliminated in consolidation. In addition, we include our share of the results of HyVia using the equity method based on our economic ownership interest and our ability to exercise significant influence over the operating and financial decisions of HyVia. Interim Financial Statements The accompanying unaudited interim condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). In the opinion of management, all adjustments, which consist solely of normal recurring adjustments, necessary to present fairly, in accordance with U.S. generally accepted accounting principles (“GAAP”), the financial position, results of operations and cash flows for all periods presented, have been made. The results of operations for the interim periods presented are not necessarily indicative of the results that may be expected for the full year. Certain information and footnote disclosures normally included in annual consolidated financial statements prepared in accordance with GAAP have been condensed or omitted. These unaudited interim condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto included in the Company’s 2020 10-K. The information presented in the accompanying unaudited interim condensed consolidated balance sheets as of December 31, 2020 has been derived from the Company’s December 31, 2020 audited consolidated financial statements. There have been no changes in our accounting policies from those reported in our 2020 10-K, except for the adoption of 2020-06, as described in the Recently Adopted Accounting Guidance section. We have also expanded our accounting policy relating to cash equivalents, and available-for-sale securities as follows: Cash Equivalents The Company considers all highly-liquid debt securities with original maturities of three months or less to be cash equivalents. At June 30, 2021, cash equivalents consisted of commercial paper and U.S. Treasury securities with original maturities of three months or less, and money market funds. Due to their short-term nature, the carrying amounts reported in the unaudited interim condensed consolidated balance sheets approximate the fair value of cash and cash equivalents. Available-for-sale securities Available-for-sale securities is comprised of commercial paper with original maturities greater than three months, U.S. Treasury securities, municipal debt, certificates of deposit and corporate bonds. We consider these securities to be Available-for-sale securities are recorded at fair value as of each balance sheet date. As of each balance sheet date, unrealized gains and losses, with the exception of credit related losses, are recorded to accumulated other comprehensive income. Any credit related losses are recognized as a credit loss allowance on the balance sheet with a corresponding adjustment to operations. Realized gains and losses are due to the sale and maturity of securities classified as available-for-sale and represent the net gain (loss) from accumulated other comprehensive income reclassifications for previously unrealized net gains on available-for-sale debt securities. Equity securities Equity securities are comprised of fixed income and equity market index mutual funds. Equity securities are valued at fair value with changes in the fair value recognized in our unaudited interim condensed consolidated statement of operations. We consider these securities to be Recent Accounting Pronouncements Recently Adopted Accounting Guidance Other than the adoption of the accounting guidance mentioned i n our 2020 10-K and ASU 2020-06 On January 1, 2021, we early adopted ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40) using the modified retrospective approach. Consequently, the Company’s 3.75% Convertible Senior Notes due 2025 (the “3.75% Convertible Senior Notes”) is now accounted for as a single liability measured at its amortized cost. This accounting change removed the impact of recognizing the equity component of the Company’s convertible notes at issuance and the subsequent accounting impact of additional interest expense from debt discount amortization. Future interest expense of the convertible notes will be lower as a result of adoption of this guidance and net loss per share will be computed using the if-converted method for convertible instruments. The cumulative effect of the accounting change upon adoption on January 1, 2021 increased the carrying amount of the 3.75% Convertible Senior Notes by $120.6 million, reduced accumulated deficit by $9.6 million and reduced additional paid-in capital by $130.2 million. Recent Accounting Guidance Not Yet Effective All issued but not yet effective accounting and reporting standards as of June 30, 2021 are either not applicable to the Company or are not expected to have a material impact on the Company.

Extended Maintenance Contracts

Extended Maintenance Contracts	6 Months Ended
Extended Maintenance Contracts	Jun. 30, 2021
Extended Maintenance Contracts
Extended Maintenance Contracts	3. Extended Maintenance Contracts On a quarterly basis, we evaluate any potential losses related to our extended maintenance contracts for fuel cell systems and related infrastructure that has been sold. We measure impairment losses at the customer contract level. The expected revenues and expenses for these contracts include all applicable expected costs of providing services over the remaining term of the contracts and the related unearned net revenue. A loss is recognized if the sum of expected costs of providing services under the contract exceeds related unearned net revenue and is recorded as a provision for loss contracts related to service in the consolidated statements of operations. A key component of these estimates is the expected future service costs. In estimating the expected future costs, the Company considers its current service cost level and applies significant judgment related to expected cost saving initiatives. The expected future cost savings will be primarily dependent upon the success of the Company’s initiatives related to increasing stack life, achieving better economies of scale for service labor, and improvements in design and operations of infrastructure. If the expected cost saving initiatives are not realized, this will increase the costs of providing services and could adversely affect our estimated contract loss accrual. The following table shows the rollforward of balance in the accrual for loss contracts, including changes due to the passage of time, additions, and changes in estimates (in thousands): Six months ended Year ended June 30, 2021 December 31, 2020 Beginning Balance $ 24,013 $ 3,702 Provision for Loss Accrual 8,179 35,473 Released to Service Cost of Sales (3,780) (2,348) Released to Provision for Warrants — (12,814) Ending Balance $ 28,412 $ 24,013

Earnings Per Share

Earnings Per Share	6 Months Ended
Earnings Per Share	Jun. 30, 2021
Earnings Per Share
Earnings Per Share	4. Earnings Per Share Basic earnings per common stock are computed by dividing net loss attributable to common stockholders by the weighted average number of common stock outstanding during the reporting period. After January 1, 2021, the date of the adoption of ASU 2020-06, in periods when we have net income, the shares of our common stock subject to the convertible notes outstanding during the period will be included in our diluted earnings per share under the if-converted method. Since the Company is in a net loss position, all common stock equivalents would be considered anti-dilutive and are therefore not included in the determination of diluted earnings per share. Accordingly, basic and diluted loss per share are the same. The potentially dilutive securities are summarized as follows: At June 30, 2021 2020 Stock options outstanding (1) 9,165,066 16,273,120 Restricted stock outstanding (2) 6,511,808 4,455,484 Common stock warrants (3) 83,518,821 110,573,392 Convertible Senior Notes (4) 39,170,766 72,872,730 Number of dilutive potential shares of common stock 138,366,461 204,174,726 (1) During the three months ended June 30, 2021 and 2020, the Company granted 117,500 and 89,649 stock options, respectively. During the six months ended June 30, 2021 and 2020, the Company granted 698,500 and 174,649 stock options, respectively. (2) During the three months ended June 30, 2021 and 2020, the Company granted 98,000 and 96,649 shares of restricted stock, respectively. During the six months ended June 30, 2021 and 2020, the Company granted 653,000 and 96,649 shares of restricted stock, respectively. (3) In April 2017, the Company issued a warrant to acquire up to 55,286,696 shares of the Company’s common stock as part of a transaction agreement with Amazon, subject to certain vesting events, as described in Note 12, “Warrant Transaction Agreements.” The warrant had been exercised with respect to 13,960,354 shares of the Company’s common stock as of June 30, 2021. In July 2017, the Company issued a warrant to acquire up to 55,286,696 shares of the Company’s common stock as part of a transaction agreement with Walmart, subject to certain vesting events, as described in Note 12, “Warrant Transaction Agreements.” The warrant had been exercised with respect to 13,094,217 shares of the Company’s common stock as of June 30, 2021. (4) In March 2018, the Company issued the 5.5% Convertible Senior Notes due 2023 (the “5.5% Convertible Senior Notes”). In September 2019, the Company issued the 7.5% Convertible Senior Note due 2023 (the “7.5% Convertible Senior Note”), which was fully converted into 16.0 million shares of common stock on July 1, 2020. In May 2020, the Company issued the 3.75% Convertible Senior Notes and repurchased $66.3 million of the 5.5% Convertible Senior Notes. In the fourth quarter of 2020, $33.5 million of the remaining 5.5% Convertible Senior Notes converted into 14.6 million shares of common stock. The remaining $160 thousand aggregate principal amount of the 5.5% Convertible Senior Notes were converted in January 2021. During the first quarter of 2021, $15.2 million of the 3.75% Convertible Senior Notes were converted, resulting in the issuance of 3,016,036 shares of common stock. There were no conversions in the second quarter of 2021.

Inventory

Inventory	6 Months Ended
Inventory	Jun. 30, 2021
Inventory
Inventory	5. Inventory Inventory as of June 30, 2021 and December 31, 2020 consisted of the following (in thousands): June 30, December 31, 2021 2020 Raw materials and supplies - production locations $ 131,932 $ 92,221 Raw materials and supplies - customer locations 14,096 12,405 Work-in-process 58,147 29,349 Finished goods 5,645 5,411 Inventory $ 209,820 $ 139,386

Equipment Related to Power Purc

Equipment Related to Power Purchase Agreements and Fuel Delivered to Customers, net	6 Months Ended
	Jun. 30, 2021
Equipment Related to Power Purchase Agreements and Fuel Delivered to Customers, net
Equipment Related to Power Purchase Agreements and Fuel Delivered to Customers, net	6. Equipment Related to Power Purchase Agreements and Fuel Delivered to Customers, net Equipment related to power purchase agreements and fuel delivered to customers, net at June 30, 2021 and December 31, 2020 consisted of the following (in thousands): June 30, December 31, 2021 2020 Equipment related to power purchase agreements and fuel delivered to customers $ 97,547 $ 92,736 Less: accumulated depreciation (18,629) (16,929) Equipment related to power purchase agreements and fuel delivered to customers, net 78,918 75,807 As of June 30, 2021, the Company had deployed long-lived assets at customer sites that had associated Power Purchase Agreements (“PPAs”). These PPAs expire over the next one Depreciation expense was $2.0 million and $2.2 million for the three months ended June 30, 2021 and 2020, respectively. Depreciation expense was $3.8 million and $4.3 million for the six months ended June 30, 2021 and 2020, respectively. The Company terminated its contractual relationship with a fuel provider effective March 31, 2021. The Company has historically leased fuel tanks from this provider. As a result of this termination, the Company recognized various costs, primarily for removal of tanks, reimbursement of unamortized installation costs, costs to temporarily provide customers with fuel during the transition period, and certain other contract settlement costs. These costs amounted to approximately $16.0 million for the six months ended June 30, 2021, which are recorded in the Company’s unaudited interim condensed consolidated statement of operations as cost of revenue – fuel delivered to customers for the six months ended June 30, 2021. The Company also purchased certain fuel tanks from the fuel provider during the three months ended June 30, 2021.

Property, Plant and Equipment

Property, Plant and Equipment	6 Months Ended
Property, Plant and Equipment	Jun. 30, 2021
Property, Plant and Equipment
Property, Plant and Equipment	7. Property, Plant and Equipment Property, plant and equipment at June 30, 2021 and December 31, 2020 consists of the following (in thousands): June 30, 2021 December 31, 2020 Land 1,165 1,165 Leasehold improvements $ 1,401 $ 1,121 Software, machinery and equipment 133,349 94,449 Property, plant, and equipment 135,915 96,735 Less: accumulated depreciation (25,440) (22,186) Property, plant, and equipment, net $ 110,475 $ 74,549 Depreciation expense related to property, plant and equipment was $1.6 million and $0.9 million for the three months ended June 30, 2021 and 2020, respectively. Depreciation expense related to property, plant and equipment was $3.3 million and $1.8 million for the six months ended June 30, 2021 and 2020, respectively.

Intangible Assets and Goodwill

Intangible Assets and Goodwill	6 Months Ended
Intangible Assets and Goodwill	Jun. 30, 2021
Intangible Assets and Goodwill
Intangible Assets and Goodwill	8. Intangible Assets and Goodwill The gross carrying amount and accumulated amortization of the Company’s acquired identifiable intangible assets as of June 30, 2021 were as follows (in thousands): Weighted Average Gross Carrying Accumulated Amortization Period Amount Amortization Total Acquired technology 10 years $ 13,150 $ (4,624) $ 8,526 Customer relationships, Non-compete agreements, Backlog & Trademark 6 years 890 (364) 526 In process research and development Indefinite 29,000 — 29,000 $ 43,040 $ (4,988) $ 38,052 The gross carrying amount and accumulated amortization of the Company’s acquired identifiable intangible assets as of December 31, 2020 were as follows (in thousands): Weighted Average Gross Carrying Accumulated Amortization Period Amount Amortization Total Acquired technology 10 years $ 13,697 $ (4,042) $ 9,655 Customer relationships, Non-compete agreements, Backlog & Trademark 6 years 890 (294) 596 In process research and development Indefinite 29,000 — 29,000 $ 43,587 $ (4,336) $ 39,251 The change in the gross carrying amount of the acquired technology from December 31, 2020 to June 30, 2021 was primarily due to foreign currency translation. Amortization expense for acquired identifiable intangible assets for the three months ended June 30, 2021 and 2020 was $0.4 million and $0.2 million, respectively. Amortization expense for acquired identifiable intangible assets for the six months ended June 30, 2021 and 2020 was $0.7 million and $0.4 million, respectively. The estimated amortization expense for subsequent years is as follows (in thousands): Remainder of 2021 $ 732 2022 1,463 2023 1,463 2024 1,442 2025 and thereafter 3,952 Total $ 9,052 Goodwill was $72.1 million and $72.4 million as of June 30, 2021 and December 31, 2020, respectively, which decreased $304 thousand due to currency translation loss for HyPulsion S.A.S., our French subsidiary. There were no impairments during the six months ended June 30, 2021 or the year ended December 31, 2020.

Long-Term Debt

Long-Term Debt	6 Months Ended
Long-Term Debt	Jun. 30, 2021
Long-Term Debt
Long-Term Debt	9. Long-Term Debt In March 2019, the Company entered into a loan and security agreement, as amended (the “Loan Agreement”), with Generate Lending, LLC (“Generate Capital”), providing for a secured term loan facility in the amount of $100 million (the “Term Loan Facility”). During the year ended December 31, 2020, the Company, under another series of amendments to the Loan Agreement, borrowed an incremental $100.0 million. As part of the amendment to the Loan Agreement, the Company’s interest rate on the secured term loan facility was reduced to 9.50% from 12.00% per annum, and the maturity date was extended to October 31, 2025 from October 6, 2022. On June 30, 2021, the outstanding balance under the Term Loan Facility was $150.8 million. In addition to the Term Loan Facility, on June 30, 2021 there was approximately $10.0 million of debt related to United Hydrogen Group, Inc. acquisition. The Loan Agreement includes covenants, limitations, and events of default customary for similar facilities. Interest and a portion of the principal amount is payable on a quarterly basis. Principal payments are funded in part by releases of restricted cash, as described in Note 19, “Commitments and Contingencies.” Based on the amortization schedule as of June 30, 2021, the aforementioned loan balance under the Term Loan Facility will be fully paid by October 31, 2025. The Company is in compliance with, or has obtained waivers for, all debt covenants. The Term Loan Facility is secured by substantially all of the Company’s and the guarantor subsidiaries’ assets, including, among other assets, all intellectual property, all securities in domestic subsidiaries and 65% of the securities in foreign subsidiaries, subject to certain exceptions and exclusions. The Loan Agreement provides that if there is an event of default due to the Company’s insolvency or if the Company fails to perform in any material respect the servicing requirements for fuel cell systems under certain customer agreements, which failure would entitle the customer to terminate such customer agreement, replace the Company or withhold the payment of any material amount to the Company under such customer agreement, then Generate Capital has the right to cause Proton Services Inc., a wholly owned subsidiary of the Company, to replace the Company in performing the maintenance services under such customer agreement. As of June 30, 2021, the Term Loan Facility requires the principal balance as of each of the following dates not to exceed the following (in thousands): December 31, 2021 $ 127,317 December 31, 2022 93,321 December 31, 2023 62,920 December 31, 2024 33,692 December 31, 2025 —

Convertible Senior Notes

Convertible Senior Notes	6 Months Ended
Convertible Senior Notes	Jun. 30, 2021
Convertible Senior Notes.
Convertible Senior Notes	10. Convertible Senior Notes 3.75% Convertible Senior Notes On May 18, 2020, the Company issued $200.0 million in aggregate principal amount of 3.75% Convertible Senior Notes due June 1, 2025, in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended, (“the Securities Act”). On May 29, 2020, the Company issued an additional $12.5 million in aggregate principal amount of 3.75% Convertible Senior Notes. At issuance in May 2020, the total net proceeds from the 3.75% Convertible Senior Notes were as follows: Amount (in thousands) Principal amount $ 212,463 Less initial purchasers' discount (6,374) Less cost of related capped calls (16,253) Less other issuance costs (617) Net proceeds $ 189,219 The 3.75% Convertible Senior Notes bear interest at a rate of 3.75% per year, payable semi-annually in arrears on June 1 and December 1 of each year, beginning on December 1, 2020. The notes will mature on June 1, 2025, unless earlier converted, redeemed or repurchased in accordance with their terms. The 3.75% Convertible Senior Notes are senior, unsecured obligations of the Company and rank senior in right of payment to any of the Company’s indebtedness that is expressly subordinated in right of payment to the notes, equal in right of payment to any of the Company’s existing and future liabilities that are not so subordinated, including the Company’s $100 million in aggregate principal amount of the 5.5% Convertible Senior Notes, effectively junior in right of payment to any of the Company’s secured indebtedness to the extent of the value of the collateral securing such indebtedness, and structurally subordinated to all indebtedness and other liabilities, including trade payables, of its current or future subsidiaries. Holders of the 3.75% Convertible Senior Notes may convert their notes at their option at any time prior to the close of the business day immediately preceding December 1, 2024 in the following circumstances: 1) during any calendar quarter commencing after March 31, 2021 if the last reported sale price of the Company’s common stock exceeds 130% of the conversion price for each of at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter; 2) during the five business days after any five consecutive trading day period (such five consecutive trading day period, the measurement period) in which the trading price per $1,000 principal amount of the 3.75% Convertible Senior Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; 3) if the Company calls any or all of the 3.75% Convertible Senior Notes for redemption, any such notes that have been called for redemption may be converted at any time prior to the close of business on the second scheduled trading day immediately preceding the redemption date; or 4) upon the occurrence of specified corporate events, as described in the indenture governing the 3.75% Convertible Senior Notes. On or after December 1, 2024, the holders of the 3.75% Convertible Senior Notes may convert all or any portion of their notes at any time prior to the close of business on the second scheduled trading day immediately preceding the maturity date regardless of the foregoing conditions. The initial conversion rate for the 3.75% Convertible Senior Notes is 198.6196 shares of the Company’s common stock per $1,000 principal amount of notes, which is equivalent to an initial conversion price of approximately $5.03 per share of the Company’s common stock, subject to adjustment upon the occurrence of specified events. Upon conversion, the Company will pay or deliver, as applicable, cash, shares of the Company’s common stock or a combination of cash and shares of the Company’s common stock, at the Company’s election. During the three months ended June 30, 2021, certain conditions allowing holders of the 3.75% Convertible Senior Notes to convert were met. The 3.75% Convertible Senior Notes are therefore convertible during the calendar quarter ending September 30, 2021 at the conversion rate discussed above. During the six months ended June 30, 2021, $15.2 million of the 3.75% Convertible Senior Notes were converted and the Company issued 3.0 million shares of common stock in conjunction with these conversions. In addition, following certain corporate events or following issuance of a notice of redemption, the Company will increase the conversion rate for a holder who elects to convert its notes in connection with such a corporate event or convert its notes called for redemption during the related redemption period in certain circumstances. The 3.75% Convertible Senior Notes will be redeemable, in whole or in part, at the Company’s option at any time, and from time to time, on or after June 5, 2023 and before the 41 st one three If the Company undergoes a “fundamental change” (as defined in the Indenture), holders may require the Company to repurchase their notes for cash all or any portion of their notes at a fundamental change repurchase price equal to 100% of the principal amount of the notes to be repurchased, plus accrued and unpaid interest, to, but excluding, the fundamental change repurchase date. The Company accounts for the 3.75% Convertible Senior Notes as a liability. We incurred transaction costs related to the issuance of the 3.75% Convertible Senior Notes of approximately $7.0 million, consisting of initial purchasers’ discount of approximately $6.4 million and other issuance costs of $0.6 million which were recorded as debt issuance cost (presented as contra debt in the unaudited interim condensed consolidated balance sheets) and are being amortized to interest expense over the term of the 3.75% Convertible Senior Notes. The 3.75% Convertible Senior Notes consisted of the following (in thousands): June 30, 2021 Principal amounts: Principal $ 197,278 Unamortized debt issuance costs (1) (5,267) Net carrying amount $ 192,011 1) Included in the unaudited interim condensed consolidated balance sheets within the 3.75% Convertible Senior Notes, net and amortized over the remaining life of the notes using the effective interest rate method. The following table summarizes the total interest expense and effective interest rate related to the 3.75% Convertible Senior Notes (in thousands, except for effective interest rate): June 30, 2021 Interest expense $ 1,850 Amortization of debt issuance costs 306 Total 2,156 Effective interest rate 4.50% Capped Call In conjunction with the pricing of the 3.75% Convertible Senior Notes, the Company entered into privately negotiated capped call transactions (the “3.75% Notes Capped Call”) with certain counterparties at a price of $16.2 million. The 3.75% Notes Capped Call covers, subject to anti-dilution adjustments, the aggregate number of shares of the Company’s common stock that underlie the initial 3.75% Convertible Senior Notes and The net cost incurred in connection with the 3.75% Notes Capped Call were recorded as a reduction to additional paid-in capital in the unaudited interim condensed consolidated balance sheets. 5.5% Convertible Senior Notes In March 2018, the Company issued $100.0 million in aggregate principal amount of the 5.5% Convertible Senior Notes due on March 15, 2023, in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act. In May 2020, the Company used a portion of the net proceeds from the issuance of the 3.75% Convertible Senior Notes to finance the cash portion of the partial repurchase of the 5.5% Convertible Senior Notes, which consisted of a repurchase of approximately $66.3 million in aggregate principal amount of the 5.5% Convertible Senior Notes in privately-negotiated transactions for aggregate consideration of $128.9 million, consisting of approximately $90.2 million in cash and approximately 9.4 million shares of the Company’s common stock. The partial repurchase of the 5.5% Convertible Senior Notes resulted in a $13.2 million gain on early debt extinguishment. In the fourth quarter of 2020, $33.5 million of the remaining 5.5% Convertible Senior Notes were converted into 14.6 million shares of common stock which resulted in a gain of approximately $4.5 million which was recorded on the consolidated statement of operations on the gain (loss) on extinguishment of debt line. On January 7, 2021, the remaining aggregate principal of $160 thousand aggregate principal amount of the 5.5% Convertible Senior Notes were converted into 69,808 shares of common stock. Interest expense and amortization for the period were immaterial. Capped Call In conjunction with the pricing of the 5.5% Convertible Senior Notes, the Company entered into privately negotiated capped call transactions (the “5.5% Notes Capped Call”) with certain counterparties at a price of $16.0 million to reduce the potential dilution to the Company’s common stock upon any conversion of the 5.5% Convertible Senior Notes and/or offset any cash payments the Company is required to make in excess of the principal amount of the converted 5.5% Convertible Senior Notes, as the case may be. The net cost incurred in connection with the 5.5% Notes Capped Call has been recorded as a reduction to additional paid-in capital in the unaudited interim condensed consolidated balance sheets. In conjunction with the pricing of the partial repurchase of the 5.5% Convertible Senior Notes, the Company terminated 100% of the 5.5% Notes Capped Call on June 5, 2020. As a result of the termination, the Company received $24.2 million, which was recorded in additional paid-in capital in the unaudited interim condensed consolidated balance sheets. Common Stock Forward In connection with the issuance of the 5.5% Convertible Senior Notes, the Company also entered into a forward stock purchase transaction, (“the Common Stock Forward”), pursuant to which the Company agreed to purchase 14,397,906 shares of its common stock for settlement on or about March 15, 2023. In connection with the issuance of the 3.75% Convertible Senior Notes and the partial repurchase of the 5.5% Convertible Senior Notes, the Company amended and extended the maturity of the Common Stock Forward to June 1, 2025. The number of shares of common stock that the Company will ultimately repurchase under the Common Stock Forward is subject to customary anti-dilution adjustments. The Common Stock Forward is subject to early settlement or settlement with alternative consideration in the event of certain corporate transactions. The net cost incurred in connection with the Common Stock Forward of $27.5 million was recorded as an increase in treasury stock in the unaudited interim condensed consolidated balance sheets. The related shares were accounted for as a repurchase of common stock. The book value of the 5.5% Notes Capped Call and Common Stock Forward are not remeasured. During the fourth quarter of 2020, the Common Stock Forward was partially settled and, as a result, the Company received 4.4 million shares of its common stock. During the first quarter of 2021, 5.9 million shares settled and were received by the Company. During the second quarter of 2021, an additional 2.2 million shares were settled and received by the Company.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
Stockholders' Equity	Jun. 30, 2021
Stockholders' Equity
Stockholders' Equity	11. Stockholders’ Equity Preferred Stock The Company has authorized 5.0 million shares of preferred stock, par value $0.01 per share. The Company’s certificate of incorporation provides that shares of preferred stock may be issued from time to time in one or more series. The Company’s Board of Directors is authorized to fix the voting rights, if any, designations, powers, preferences, qualifications, limitations and restrictions thereof, applicable to the shares of each series. The Company has authorized Series A Junior Participating Cumulative Preferred Stock, par value $0.01 per share. As of June 30, 2021 and December 31, 2020, there were no shares of Series A Junior Participating Cumulative Preferred Stock issued and outstanding. Common Stock and Warrants The Company has one class of common stock, par value $0.01 per share. Each share of the Company’s common stock is entitled to one vote on all matters submitted to stockholders. In February 2021, the Company completed the previously announced sale of its common stock in connection with a strategic partnership with SK Holdings to accelerate the use of hydrogen as an alternative energy source in Asian markets. The Company sold 54,966,188 shares of its common stock to a subsidiary of SK Holdings at a purchase price of $29.2893 per share, or an aggregate purchase price of approximately $1.6 billion. In January and February 2021, the Company issued and sold in a registered equity offering an aggregate of 32.2 million shares of its common stock at a purchase price of $65.00 per share for net proceeds of approximately $1.8 billion. In November 2020, the Company issued and sold in a registered equity offering an aggregate of 43,700,000 shares of its common stock at a purchase price of $22.25 per share for net proceeds of approximately $927.3 million. In August 2020, the Company issued and sold in a registered equity offering an aggregate of 35,276,250 shares of its common stock at a purchase price of $10.25 per share for net proceeds of approximately $344.4 million. There were 570,922,157 and 458,051,401 shares of common stock outstanding as of June 30, 2021 and December 31, 2020, respectively. During 2017, warrants to purchase up to 110,573,392 shares of common stock were issued in connection with transaction agreements with Amazon and Walmart, as discussed in Note 12, “Warrant Transaction Agreements.” At both June 30, 2021 and December 31, 2020, a total of 68,380,913 warrants had vested. Warrants were exercised with respect to 5,819,652 shares during the fourth quarter of 2020. In the first quarter of 2021, warrants were exercised with respect to 16,489,014 shares of common stock. In the second quarter of 2021, warrants were exercised with respect to an additional 4,745,905 shares of common stock. These warrants are measured at fair value at the time of grant or modification and are classified as equity instruments on the unaudited interim condensed consolidated balance sheets. At Market Issuance Sales Agreement On April 13, 2020, the Company entered into the At Market Issuance Sales Agreement with B. Riley Financial (“B. Riley”), as sales agent, pursuant to which the Company may offer and sell, from time to time through B. Riley, shares of Company common stock having an aggregate offering price of up to $75.0 million. As of the date of this filing, the Company has not issued any shares of common stock pursuant to the At Market Issuance Sales Agreement.

Warrant Transaction Agreements

Warrant Transaction Agreements	6 Months Ended
Warrant Transaction Agreements	Jun. 30, 2021
Warrant Transaction Agreements
Warrant Transaction Agreements	12. Warrant Transaction Agreements Amazon Transaction Agreement On April 4, 2017, the Company and Amazon entered into a Transaction Agreement (the “Amazon Transaction Agreement”), pursuant to which the Company agreed to issue to Amazon.com NV Investment Holdings LLC, a wholly owned subsidiary of Amazon, a warrant (the “Amazon Warrant”) to acquire up to 55,286,696 shares of the Company’s common stock (the “Amazon Warrant Shares”), subject to certain vesting events described below. The Company and Amazon entered into the Amazon Transaction Agreement in connection with existing commercial agreements between the Company and Amazon with respect to the deployment of the Company’s GenKey fuel cell technology at Amazon distribution centers. The existing commercial agreements contemplate, but do not guarantee, future purchase orders for the Company’s fuel cell technology. The vesting of the Amazon Warrant Shares was conditioned upon payments made by Amazon or its affiliates (directly or indirectly through third parties) pursuant to the existing commercial agreements. Under the terms of the original Amazon Warrant, the first tranche of the 5,819,652 Amazon Warrant Shares vested upon execution of the Amazon Warrant, and the remaining Amazon Warrant Shares vest based on Amazon’s payment of up to $600.0 million to the Company in connection with Amazon’s purchase of goods and services from the Company. The $6.7 million fair value of the first tranche of the Amazon Warrant Shares, was recognized as selling, general and administrative expense upon execution of the Amazon Warrant. Provision for the second and third tranches of Amazon Warrant Shares is recorded as a reduction of revenue, because they represent consideration payable to a customer. The fair value of the second tranche of Amazon Warrant Shares was measured at January 1, 2019, upon adoption of ASU 2019-08. The second tranche of 29,098,260 Amazon Warrant Shares vested in four equal installments, as Amazon or its affiliates, directly or indirectly through third parties, made an aggregate of $50.0 million in payments for goods and services to the Company, up to payments totaling $200.0 million in the aggregate. The last installment of the second tranche vested on November 2, 2020. Revenue reductions of $9.0 million, $4.1 million and $9.8 million associated with the second tranche of Amazon Warrant Shares were recorded in 2020, 2019 and 2018, respectively, under the terms of the original Amazon Warrant. Under the terms of the original Amazon Warrant, the third tranche of 20,368,784 Amazon Warrant Shares vests in eight equal installments, as Amazon or its affiliates, directly or indirectly through third parties, made an aggregate of $50.0 million in payments for goods and services to the Company, up to payments totaling $400.0 million in the aggregate. The measurement date for the third tranche of Amazon Warrant Shares was November 2, 2020, when their exercise price was determined, as discussed further below. The fair value of the third tranche of Amazon Warrant Shares was determined to be $10.57 each. During 2020, revenue reductions of $24.1 million associated with the third tranche Amazon Warrant Shares were recorded under the terms of the original Amazon Warrant, prior to the December 31, 2020 waiver described below. On December 31, 2020, the Company waived the remaining vesting conditions under the Amazon Warrant, which resulted in the immediate vesting of all the third tranche of the Amazon Warrant Shares and recognition of an additional $399.7 million reduction to revenue. The $399.7 million reduction to revenue resulting from the December 31, 2020 waiver was determined based upon a probability assessment of whether the underlying shares would have vested under the terms of the original Amazon Warrant. Based upon the Company’s projections of probable future cash collections from Amazon (i.e., a Type I share based payment modification), a reduction of revenue associated with 5,354,905 Amazon Warrant Shares was recognized at their previously measured November 2, 2020 fair value of $10.57 per warrant. A reduction of revenue associated with the remaining 12,730,490 Amazon Warrant Shares was recognized at their December 31, 2020 fair value of $26.95 each, based upon the Company’s assessment that associated future cash collections from Amazon were not deemed probable (i.e., a Type III share based payment modification). The $399.7 million reduction to revenue was recognized during the year ended December 31, 2020 because the Company concluded such amount was not recoverable from the margins expected from future purchases by Amazon under the Amazon Warrant, and no exclusivity or other rights were conferred to the Company in connection with the December 31, 2020 waiver. Additionally, for the year ended December 31, 2020, the Company recorded a reduction to the provision for warrants of $12.8 million in connection with the release of the service loss accrual. At December 31, 2020, all 55,286,696 of the Amazon Warrant Shares had vested. For service contracts entered into prior to December 31, 2020, the warrant charge associated with that revenue was capitalized and is subsequently amortized over the life of the service contract. The total amount of provision for common stock warrants recorded as a reduction of revenue for the Amazon Warrant during the three months ended June 30, 2021 and 2020 was $105 thousand and $3.4 million, respectively. The amount of provision for common stock warrants recorded as a reduction of revenue for the Amazon Warrant during the six months ended June 30, 2021 and 2020 was $209 thousand and $4.7 million, respectively. During the three months ended March 31, 2021 and June 30, 2021, the Amazon Warrant was exercised with respect to 9,214,449 shares of common stock and 4,745,905 shares of common stock. In July 2021, the Amazon Warrant was exercised with respect to an additional 3,501,640 shares of common stock. The exercise price for the first and second tranches of Amazon Warrant Shares was $1.1893 per share. The exercise price of the third tranche of Amazon Warrant Shares was $13.81 per share, which was determined pursuant to the terms of the Amazon Warrant as an amount equal to ninety percent (90%) of the 30-day volume weighted average share price of the Company’s common stock as of November 2, 2020, the final vesting date of the second tranche of Amazon Warrant Shares. The Amazon Warrant is exercisable through April 4, 2027. The Amazon Warrant provides for net share settlement that, if elected by the holder, will reduce the number of shares issued upon exercise to reflect net settlement of the exercise price. The Amazon Warrant provides for certain adjustments that may be made to the exercise price and the number of shares of common stock issuable upon exercise due to customary anti-dilution provisions based on future events. The Amazon Warrant is classified as an equity instrument. Fair value of the Amazon Warrant at December 31, 2020 and November 2, 2020 was based on the Black Scholes Option Pricing Model, which is based, in part, upon level 3 unobservable inputs for which there is little or no market data, requiring the Company to develop its own assumptions. The Company used the following assumptions for its Amazon Warrant: December 31, 2020 November 2, 2020 Risk-free interest rate 0.58% 0.58% Volatility 75.00% 75.00% Expected average term 6.26 6.42 Exercise price $13.81 $13.81 Stock price $33.91 $15.47 Walmart Transaction Agreement On July 20, 2017, the Company and Walmart entered into a Transaction Agreement (the “Walmart Transaction Agreement”), pursuant to which the Company agreed to issue to Walmart a warrant (the “Walmart Warrant”) to acquire up to 55,286,696 shares of the Company’s common stock, subject to certain vesting events (the “Walmart Warrant Shares”). The Company and Walmart entered into the Walmart Transaction Agreement in connection with existing commercial agreements between the Company and Walmart with respect to the deployment of the Company’s GenKey fuel cell technology across various Walmart distribution centers. The existing commercial agreements contemplate, but do not guarantee, future purchase orders for the Company’s fuel cell technology. The vesting of the warrant shares conditioned upon payments made by Walmart or its affiliates (directly or indirectly through third parties) pursuant to transactions entered into after January 1, 2017 under existing commercial agreements. The majority of the Walmart Warrant Shares will vest based on Walmart’s payment of up to $600.0 million to the Company in connection with Walmart’s purchase of goods and services from the Company. The first tranche of 5,819,652 Walmart Warrant Shares vested upon the execution of the Walmart Warrant and was fully exercised as of December 31, 2020. Accordingly, $10.9 million, the fair value of the first tranche of Walmart Warrant Shares, was recorded as a provision for common stock warrants and presented as a reduction to revenue on the consolidated statements of operations during 2017. All future provision for common stock warrants is measured based on their grant-date fair value and recorded as a charge against revenue. The second tranche of 29,098,260 Walmart Warrant Shares vests in four installments of 7,274,565 Walmart Warrant Shares each time Walmart or its affiliates, directly or indirectly through third parties, make an aggregate of $50.0 million in payments for goods and services to the Company, up to payments totaling $200.0 million in the aggregate. The exercise price for the first and second tranches of Walmart Warrant Shares is $2.1231 per share. After Walmart has made payments to the Company totaling $200.0 million, the third tranche of 20,368,784 Walmart Warrant Shares will vest in eight installments of 2,546,098 Walmart Warrant Shares each time Walmart or its affiliates, directly or indirectly through third parties, make an aggregate of $50.0 million in payments for goods and services to the Company, up to payments totaling $400.0 million in the aggregate. The exercise price of the third tranche of Walmart Warrant Shares will be an amount per share equal to ninety percent (90%) of the 30-day volume weighted average share price of the common stock as of the final vesting date of the second tranche of Walmart Warrant Shares, provided that, with limited exceptions, the exercise price for the third tranche will be no lower than $1.1893. The Walmart Warrant is exercisable through July 20, 2027. The Walmart Warrant provides for net share settlement that, if elected by the holder, will reduce the number of shares issued upon exercise to reflect net settlement of the exercise price. The Walmart Warrant provides for certain adjustments that may be made to the exercise price and the number of shares of common stock issuable upon exercise due to customary anti-dilution provisions based on future events. The Walmart Warrant is classified as an equity instrument. At both June 30, 2021 and December 31, 2020, 13,094,217 of the Walmart Warrant Shares had vested. The total amount of provision for common stock warrants recorded as a reduction of revenue for the Walmart Warrant during the three months ended June 30, 2021 and 2020 was $1.6 million and $1.0 million, respectively. The amount of provision for common stock warrants recorded as a reduction of revenue for the Walmart Warrant during the six months ended June 30, 2021 and 2020 was $3.2 million and $1.9 million, respectively. During the three months ended March 31, 2021, the Walmart Warrant had been exercised with respect to 7,274,565 shares of common stock. There were no exercises during the three months ended June 30, 2021.

Revenue

Revenue	6 Months Ended
Revenue	Jun. 30, 2021
Revenue
Revenue	13. Revenue Disaggregation of revenue The following table provides information about disaggregation of revenue (in thousands): Major products/services lines Three months ended June 30, Six months ended June 30, 2021 2020 2021 2020 Sales of fuel cell systems $ 59,169 $ 40,785 $ 85,588 $ 55,425 Sale of hydrogen installations and other infrastructure 40,109 6,961 60,462 12,789 Services performed on fuel cell systems and related infrastructure 5,675 6,236 11,720 12,757 Power Purchase Agreements 8,361 6,579 16,187 13,000 Fuel delivered to customers 11,121 7,372 22,248 14,705 Other 122 62 310 138 Net revenue $ 124,557 $ 67,995 $ 196,515 $ 108,814 Contract balances The following table provides information about receivables, contract assets and contract liabilities from contracts with customers (in thousands): June 30, December 31, 2021 2020 Accounts receivable $ 91,359 $ 43,041 Contract assets 11,549 18,189 Contract liabilities 93,665 76,285 Contract assets relate to contracts for which revenue is recognized on a straight-line basis, however billings escalate over the life of a contract. Contract assets also include amounts recognized as revenue in advance of billings to customers, which are dependent upon the satisfaction of another performance obligation. These amounts are included within prepaid expenses and other current assets on the accompanying unaudited interim condensed consolidated balance sheets. The contract liabilities relate to the advance consideration received from customers for services that will be recognized over time (primarily fuel cell and related infrastructure services) and advance consideration received from customers prior to delivery of products. As of June 30, 2021, the amount of contract liabilities included within deferred revenue was $72.3 million and the amount of contract liabilities within other current liabilities was $21.4 million on the accompanying unaudited interim condensed consolidated balance sheets. As of December 31, 2020, the amount of contract liabilities included within deferred revenue was $56.2 million and the amount of contract liabilities within other current liabilities was $20.1 million. Significant changes in the contract assets and the contract liabilities balances during the period are as follows (in thousands): Contract assets Six months ended June 30, 2021 Transferred to receivables from contract assets recognized at the beginning of the period $ (7,106) Revenue recognized and not billed as of the end of the period 466 Net change in contract assets (6,640) Contract liabilities Six months ended June 30, 2021 Increases due to cash received, net of amounts recognized as revenue during the period $ 49,628 Revenue recognized that was included in the contract liability balance as of the beginning of the period (32,248) Net change in contract liabilities $ 17,380 Estimated future revenue The following table includes estimated revenue included in the backlog expected to be recognized in the future (sales of fuel cell systems and hydrogen installations are expected to be recognized as revenue within one year; sales services five June 30, 2021 Sales of fuel cell systems $ 55,348 Sale of hydrogen installations and other infrastructure 52,193 Services performed on fuel cell systems and related infrastructure 103,505 Power Purchase Agreements 196,903 Fuel delivered to customers 63,632 Other rental income 2,504 Total estimated future revenue $ 474,085 Contract costs Contract costs consist of capitalized commission fees and other expenses related to obtaining or fulfilling a contract. Capitalized contract costs at June 30, 2021 and December 31, 2020 were $1.2 million and $1.5 million, respectively.

Income Taxes

Income Taxes	6 Months Ended
Income Taxes	Jun. 30, 2021
Income Taxes
Income Taxes	14. Income Taxes The Company did not record any income tax expense or benefit for the three or six months ended June 30, 2021. The Company recognized an income tax benefit for the three and six months ended June 30, 2020 of $17.4 million. Income tax benefit for the three and six months ended June 30, 2020 included $12.2 million resulting from the intraperiod tax allocation rules under Accounting Standards Codification (“ASC”) Topic 740-20, Intraperiod Tax Allocation The net deferred tax asset generated from the Company’s net operating loss has been offset by a full valuation allowance because it is more likely than not that the tax benefits of the net operating loss carry forward will not be realized. The Company recognizes accrued interest and penalties related to unrecognized tax benefits, if any, as a component of income tax expense.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
Fair Value Measurements	Jun. 30, 2021
Fair Value Measurements
Fair Value Measurements	15. Fair Value Measurements The Company records the fair value of assets and liabilities in accordance with ASC 820, Fair Value Measurement In addition to defining fair value, ASC 820 expands the disclosure requirements around fair value and establishes a fair value hierarchy for valuation inputs. The hierarchy prioritizes the inputs into three levels based on the extent to which inputs used in measuring fair value are observable in the market. Each fair value measurement is reported in one of the three levels, which is determined by the lowest level input that is significant to the fair value measurement in its entirety. These levels are: ● Level 1 — quoted prices (unadjusted) in active markets for identical assets or liabilities. ● Level 2 — quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument. ● Level 3 — unobservable inputs reflecting management’s own assumptions about the inputs used in pricing the asset or liability at fair value. The fair values of the Company’s investments are based upon prices provided by an independent pricing service. Management has assessed and concluded that these prices are reasonable and has not adjusted any prices received from the independent provider. Securities reported at fair value utilizing Level 1 inputs represent assets whose fair value is determined based upon observable unadjusted quoted market prices for identical assets in active markets. Level 2 securities represent assets whose fair value is determined using observable market information such as previous day trade prices, quotes from less active markets or quoted prices of securities with similar characteristics. There were no transfers between Level 1 Level 2 Level the six months Assets and liabilities measured at fair value on a recurring basis are summarized below (in thousands): As of June 30, 2021 Carrying Fair Fair Value Measurements Amount Value Level 1 Level 2 Level 3 Assets Cash equivalents (1) $ 141,313 $ 141,313 $ 87,573 $ 53,740 $ — Corporate bonds 705,084 705,084 — 705,084 — Commercial paper 329,722 329,722 — 329,722 — U.S. Treasuries 170,477 170,477 170,477 — — Municipal debt 9,984 9,984 — 9,984 — Certificates of deposit 27,454 27,454 — 27,454 — Equity securities 120,302 120,302 120,302 — — Liabilities Contingent consideration 9,990 9,990 — — 9,990 Convertible senior notes 192,011 1,320,194 — 1,320,194 — Long-term debt 160,484 160,484 — — 160,484 Finance obligations 195,805 195,805 — — 195,805 As of December 31, 2020 Carrying Fair Fair Value Measurements Amount Value Level 1 Level 2 Level 3 Liabilities Contingent consideration 9,760 9,760 — — 9,760 Convertible senior notes 85,640 1,272,766 — 1,272,766 — Long-term debt 175,402 175,402 — — 175,402 Finance obligations 181,553 181,553 — — 181,553 (1) Included in “Cash and cash equivalents” in our unaudited interim condensed consolidated balance sheets as of June 30, 2021. The fair values for available-for-sale and equity securities are based on prices obtained from independent pricing services. Available-for-sale securities are characterized as Level 2 assets, as their fair values are determined using observable market inputs. Equity securities are characterized as Level 1 assets, as their fair values are determined using active markets for identical assets.

Operating and Finance Lease Lia

Operating and Finance Lease Liabilities	6 Months Ended
Operating and Finance Lease Liabilities	Jun. 30, 2021
Operating and Finance Lease Liabilities
Operating and Finance Lease Liabilities	16. Operating and Finance Lease Liabilities As of June 30, 2021, the Company had operating leases, as lessee, primarily associated with sale/leaseback transactions that are partially secured by restricted cash, security deposits and pledged escrows (see also Note 1, “Nature of Operations”) as summarized below. These leases expire over the next one Leases contain termination clauses with associated penalties, the amount of which cause the likelihood of cancellation to be remote. At the end of the lease term, the leased assets may be returned to the lessor by the Company, the Company may negotiate with the lessor to purchase the assets at fair market value, or the Company may negotiate with the lessor to renew the lease at market rental rates. No residual value guarantees are contained in the leases. No financial covenants are contained within the lease, however there are customary operational covenants such as assurance the Company properly maintains the leased assets and carries appropriate insurance, etc. The leases include credit support in the form of either cash, collateral or letters of credit. See Note 19, “Commitments and Contingencies” for a description of cash held as security associated with the leases. The Company has finance leases associated with its property and equipment in Latham, New York and at fueling customer locations. The fair value of this finance obligation approximated the carrying value as of June 30, 2021. Future minimum lease payments under operating and finance leases (with initial or remaining lease terms in excess of one year) as of June 30, 2021 were as follows (in thousands): Finance Total Operating Lease Lease Lease Liability Liability Liabilities Remainder of 2021 $ 17,298 $ 1,826 $ 19,124 2022 34,579 3,731 38,310 2023 34,636 3,708 38,344 2024 34,636 3,715 38,351 2025 and thereafter 73,276 4,921 78,197 Total future minimum payments 194,425 17,901 212,326 Less imputed interest (52,307) (2,793) (55,100) Total $ 142,118 $ 15,108 $ 157,226 Rental expense for all operating leases was $8.2 million and $7.8 million for the three months ended June 30, 2021 and 2020, respectively. Rental expense for all operating leases was $16.3 million and $12.5 million for the six months ended June 30, 2021 and 2020, respectively. The gross profit on sale/leaseback transactions for all operating leases was $19.5 million and $14.4 million for the three months ended June 30, 2021 and 2020, respectively. The gross profit on sale/leaseback transactions for all operating leases was $35.4 million and $19.7 million for the six months ended June 30, 2021 and 2020, respectively. Right of use assets for sale/leaseback transactions obtained in exchange for new operating lease liabilities was $24.0 million and $2.9 million for the three months ended June 30, 2021 and 2020, respectively. Right of use assets for sale/leaseback transactions obtained in exchange for new operating lease liabilities was $35.9 million and $8.1 million for the six months ended June 30, 2021 and 2020, respectively. At June 30, 2021 and December 31, 2020, the right of use assets associated with operating leases was $172.3 million and $136.9 million, respectively. The accumulated depreciation for these right of use assets was $26.5 million and $19.9 million at June 30, 2021 and December 31, 2020, respectively. At June 30, 2021 and December 31, 2020, the right of use assets associated with finance leases was $17.3 million and $5.7 million, respectively. The accumulated depreciation for these right of use assets was $380 thousand and $102 thousand at June 30, 2021 and December 31, 2020, respectively. At June 30, 2021 and December 31, 2020, security deposits associated with sale/leaseback transactions were $3.1 million and $5.8 million, respectively, and were included in other assets in the consolidated balance sheets. Other information related to the operating leases are presented in the following table: Six months ended Six months ended June 30, 2021 June 30, 2020 Cash payments (in thousands) $ 16,081 $ 9,674 Weighted average remaining lease term (years) 5.82 4.34 Weighted average discount rate 11.4% 12.1% Right of use assets obtained in exchange for new finance lease liabilities were $6.5 million and $0.7 million for the three months ended June 30, 2021 and 2020, respectively. Right of use assets obtained in exchange for new finance lease liabilities were $12.1 million and $0.7 million for the six months ended June 30, 2021 and 2020, respectively. Other information related to the finance leases are presented in the following table: Six months ended Six months ended June 30, 2021 June 30, 2020 Cash payments (in thousands) $ 1,166 $ 132 Weighted average remaining lease term (years) 4.86 6.74 Weighted average discount rate 6.9% 9.6%

Finance Obligations

Finance Obligations	6 Months Ended
Finance Obligations	Jun. 30, 2021
Finance Obligations
Finance Obligations	17. Finance Obligation The Company has sold future services to be performed associated with certain sale/leaseback transactions and recorded the balance as a finance obligation. The outstanding balance of this obligation at June 30, 2021 was $176.3 million, $27.3 million and $149.0 million of which was classified as short-term and long-term, respectively, on the accompanying consolidated balance sheet. The outstanding balance of this obligation at December 31, 2020 was $157.7 million, $24.2 million and $133.5 million of which was classified as short-term and long-term, respectively. The amount is amortized using the effective interest method. The fair value of this finance obligation approximated the carrying value as of June 30, 2021 and December 31, 2020. In prior periods, the Company entered into sale/leaseback transactions that were accounted for as financing transactions and reported as part of finance obligations. The outstanding balance of finance obligations related to sale/leaseback transactions at June 30, 2021 was $19.5 million, $6.5 million and $13.0 million of which was classified as short-term and long-term, respectively on the accompanying consolidated balance sheet. The outstanding balance of this obligation at December 31, 2020 was $23.9 million, $8.0 million and $15.9 million of which was classified as short-term and long-term, respectively on the accompanying consolidated balance sheets. The fair value of this finance obligation approximated the carrying value as of both June 30, 2021 and December 31, 2020. Future minimum payments under finance obligations notes above as of June 30, 2021 were as follows (in thousands): Total Sale of Future Sale/leaseback Finance revenue - debt financings Obligations Remainder of 2021 $ 23,525 $ 4,212 $ 27,737 2022 46,165 4,975 51,140 2023 46,165 3,148 49,313 2024 46,165 16,154 62,319 2025 and thereafter 72,708 — 72,708 Total future minimum payments 234,728 28,489 263,217 Less imputed interest (58,461) (8,951) (67,412) Total $ 176,267 $ 19,538 $ 195,805 Other information related to the above finance obligations are presented in the following table: Six months ended Six months ended June 30, 2021 June 30, 2020 Cash payments (in thousands) $ 26,508 $ 20,148 Weighted average remaining term (years) 4.9 4.3 Weighted average discount rate 11.3% 11.2%

Investments

Investments	6 Months Ended
Investments	Jun. 30, 2021
Investments
Investments	18. Investments The amortized cost, gross unrealized gains and losses, fair value of those investments classified as available-for-sale, and allowance for credit losses at June 30, 2021 are summarized as follows (in thousands): Amortized Gross Gross Fair Allowance for Cost Unrealized Gains Unrealized Losses Value Credit Losses Corporate bonds $ 707,022 $ 51 $ (1,989) $ 705,084 — Commercial paper 329,471 253 (2) 329,722 — Certificates of deposit 27,460 — (6) 27,454 — U.S. Treasuries 170,672 — (195) 170,477 — Municipal debt 9,993 — (9) 9,984 — Total $ 1,244,618 $ 304 $ (2,201) $ 1,242,721 $ — The cost, gross unrealized gains and losses, and fair value of those investments classified as equity securities at June 30, 2021 are summarized as follows (in thousands): June 30, 2021 Gross Gross Fair Cost Unrealized Gains Unrealized Losses Value Fixed income mutual funds $ 89,962 $ 17 $ (81) $ 89,898 Exchange traded mutual funds 30,016 388 — 30,404 Total $ 119,978 $ 405 $ (81) $ 120,302 A summary of the amortized cost and fair value of investments classified as available-for-sale, by contractual maturity, as of June 30, 2021 is as follows (in thousands): June 30, 2021 Amortized Fair Maturity: Cost Value Within one year $ 717,531 $ 717,285 After one through five years 527,087 525,436 Total $ 1,244,618 $ 1,242,721

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Jun. 30, 2021
Commitments and Contingencies
Commitments and Contingencies	19. Commitments and Contingencies Restricted Cash In connection with certain of the above noted sale/leaseback agreements, cash of $243.5 million was required to be restricted as security as of June 30, 2021, which restricted cash will be released over the lease term. As of June 30, 2021, the Company also had certain letters of credit backed by restricted cash totaling $143.7 million that are security for the above noted sale/leaseback agreements. Litigation Legal matters are defended and handled in the ordinary course of business. Liabilities for loss contingencies arising from claims, assessments, litigation, fines, and penalties and other sources are recorded when it is probable that a liability has been incurred and the amount can be reasonably estimated. Legal costs incurred in connection with loss contingencies are expensed as incurred. The Company has not recorded any accruals related to any legal matters. Concentrations of Credit Risk Financial instruments that potentially subject the Company to credit risk consist principally of cash, cash equivalents, restricted cash, accounts receivable and marketable securities. Cash and restricted cash are maintained in accounts with financial institutions, which, at times may exceed the Federal depository insurance coverage of $0.25 million. The Company has not experienced losses on these accounts and management believes, based upon the quality of the financial institutions, that the credit risk with regard to these deposits is not significant. The Company’s available-for-sale securities consists primarily of investments in commercial paper, U.S. Treasury securities, municipal debt and short-term high credit quality corporate debt securities. Equity securities are comprised of fixed income and equity market index mutual funds. Concentrations of credit risk with respect to receivables exist due to the limited number of select customers with whom the Company has commercial sales arrangements. To mitigate credit risk, the Company performs appropriate evaluation of a prospective customer’s financial condition. At June 30, 2021, one customer comprised 78.5% of the total accounts receivable balance. At December 31, 2020, three customers comprised 73.9% of the total accounts receivable balance. For purposes of assigning a customer to a sale/leaseback transaction completed with a financial institution, the Company considers the end user of the assets to be the ultimate customer. For the three and six months ended June 30, 2021, 81.3% and 77.7%, of total consolidated revenues were associated with three customers, respectively. For the three and six months ended June 30, 2020, 83.9% and 77.9% of total consolidated revenues were associated primarily with two customers, respectively.

Employee Benefit Plans

Employee Benefit Plans	6 Months Ended
Employee Benefit Plans	Jun. 30, 2021
Employee Benefit Plans
Employee Benefit Plans	20. Employee Benefit Plans 2011 Stock Option and Incentive Plan On May 12, 2011, the Company’s stockholders approved the 2011 Stock Option and Incentive Plan (the “2011 Plan”). The 2011 Plan provided for the issuance of up to a maximum number of shares of common stock equal to the sum of (i) 1,000,000, plus (ii) the number of shares of common stock underlying any grants pursuant to the 2011 Plan or the Plug Power Inc. 1999 Stock Option and Incentive Plan that are forfeited, canceled, repurchased or are terminated (other than by exercise). The shares may be issued pursuant to stock options, stock appreciation rights, restricted stock awards and certain other equity-based awards granted to employees, directors and consultants of the Company. No further grants may be made under the 2011 Plan after May 12, 2021. Through various amendments to the 2011 Plan approved by the Company’s stockholders, the number of shares of the Company’s common stock authorized for issuance under the 2011 Plan has been increased to 42.4 million. The Company recorded expense of approximately $11.1 million and $2.5 million, for the three months ended June 30, 2021 and 2020, respectively, in connection with the 2011 Plan. The Company recorded expense of approximately $19.6 million and $5.0 million, for the six months ended June 30, 2021 and 2020, respectively, in connection with the 2011 Plan. In July 2021, the 2021 Stock Option Incentive Plan (the “2021 Plan”) was approved by the Company’s stockholders, which provides for the sum of 22,500,000 shares in addition to 473,491 shares of common stock that are available for grant under the 2011 Plan to be issued under the 2021 Plan. At June 30, 2021, there were outstanding options to purchase approximately 9.2 million shares of common stock. Options for employees issued under this plan generally vest in equal annual installments over three years and expire ten years after issuance. Options granted to members of the Board generally vest one year after issuance. To date, options granted under the 2011 Plan have vesting provisions ranging from one Compensation cost associated with employee stock options represented approximately $4.3 million and $1.5 million of the total share-based payment expense recorded for the three months ended June 30, 2021 and June 30, 2020, respectively. Compensation cost associated with employee stock options represented approximately $7.6 million and $2.9 million of the total share-based payment expense recorded for the six months ended June 30, 2021 and June 30, 2020, respectively. The Company estimates the fair value of stock options using a Black-Scholes valuation model, and the resulting fair value is recorded as compensation cost on a straight-line basis over the option vesting period. Key inputs and assumptions used to estimate the fair value of stock options include the grant price of the award, the expected option term, volatility of the Company’s stock, an appropriate risk-free rate, and the Company’s dividend yield. Estimates of fair value are not intended to predict actual future events or the value ultimately realized by employees who receive equity awards, and subsequent events are not indicative of the reasonableness of the original estimates of fair value made by the Company. The assumptions made for purposes of estimating fair value under the Black-Scholes model for the 698,500 and 174,649 options granted during the six months ended June 30, 2021 and 2020, respectively, were as follows: June 30, June 30, 2021 2020 Expected term of options (years) 5 6 Risk free interest rate 0.61% - 1.04% 0.45% - 1.37% Volatility 72.46% - 73.69% 64.19% - 64.80% There was no expected dividend yield for the employee stock options granted. The Company has historically used the simplified method in determining its expected term of all its stock option grants in all periods presented. The simplified method was used because the Company did not believe historical exercise data provided a reasonable basis for the expected term of its grants, primarily as a result of the limited number of stock option exercises that have historically occurred. Due to the recent increase in exercise activity at the Company, beginning in the second quarter of 2021, the expected term is based on historical experience. The estimated stock price volatility was derived from the Company’s actual historic stock prices over the past five years, which represents the Company’s best estimate of expected volatility. A summary of stock option activity for the six months ended June 30, 2021 is as follows (in thousands except share amounts): Weighted Weighted Average Average Remaining Aggregate Exercise Contractual Intrinsic Shares Price Terms Value Options outstanding at December 31, 2020 10,284,498 $ 5.78 7.8 $ 289,316 Granted 698,500 46.82 — — Exercised (1,812,099) 2.65 — — Forfeited (5,833) 6.78 — — Expired — — — — Options outstanding at June 30, 2021 9,165,066 $ 9.51 7.9 $ 226,164 Options exercisable at June 30, 2021 2,523,341 2.17 5.6 80,808 Options unvested at June 30, 2021 6,641,725 $ 12.30 8.7 $ 145,356 The weighted average grant-date fair value of options granted during the three months ended June 30, 2021 and 2020 was $29.23 and $4.88, respectively. The weighted average grant-date fair value of options granted during the six months ended June 30, 2021 and 2020 was $46.67 and $7.73, respectively. As of June 30, 2021, there was approximately $38.3 million of unrecognized compensation cost related to stock option awards to be recognized over the next three years. The total fair value of stock options that vested during the three months ended June 30, 2021 and 2020 was approximately $432 thousand and $493 thousand, respectively. The total fair value of stock options that vested during the six months ended June 30, 2021 and 2020 was approximately $520 thousand and $516 thousand, respectively. Restricted stock awards generally vest in equal installments over a period of one A summary of restricted stock activity for the year ended June 30, 2021 is as follows (in thousands except share amounts): Aggregate Intrinsic Shares Value Unvested restricted stock at December 31, 2020 5,874,642 $ — Granted 653,000 — Vested (149,650) — Forfeited (5,833) — Unvested restricted stock at June 30, 2021 6,372,159 $ 217,864 401(k) Savings & Retirement Plan The Company offers a 401(k) Savings & Retirement Plan to eligible employees meeting certain age and service requirements. This plan permits participants to contribute 100% of their salary, up to the maximum allowable by the Internal Revenue Service regulations. Participants are immediately vested in their voluntary contributions plus actual earnings or less actual losses thereon. Participants are vested in the Company’s matching contribution based on years of service completed. Participants are fully vested upon completion of three years of service. During 2018, the Company began funding its matching contribution in a combination of cash and common stock. The Company issued 12,513 shares of common stock and 175,978 shares of common stock pursuant to the Plug Power Inc. 401(k) Savings & Retirement Plan during the six months ended June 30, 2021 and 2020, respectively. The Company’s expense for this plan was approximately $0.9 million, and $0.8 million for the three months ended June 30, 2021 and 2020, respectively. The Company’s expense for this plan was approximately $2.2 million, and $1.3 million for the six months ended June 30, 2021 and 2020, respectively. Non-Employee Director Compensation Each non-employee director is paid an annual retainer for his or her service, in the form of either cash or stock compensation. The Company granted 2,585 shares of common stock and 7,657 shares of common stock to non-employee directors as compensation for the three months ended June 30, 2021 and 2020, respectively. The Company granted 5,238 shares of common stock and 22,490 shares of common stock to non-employee directors as compensation for the six months ended June 30, 2021 and 2020, respectively. All common stock issued is fully vested at the time of issuance and is valued at fair value on the date of issuance. The Company’s share-based compensation expense in connection with non-employee director compensation was approximately $94 thousand and $55 thousand for the three months ended June 30, 2021 and 2020, respectively. The Company’s share-based compensation expense in connection with non-employee director compensation was approximately $179 thousand and $111 thousand for the six months ended June 30, 2021 and 2020, respectively.

Subsequent Events

Subsequent Events	6 Months Ended
Subsequent Events	Jun. 30, 2021
Subsequent Events
Subsequent Events	21. Subsequent Events

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2021
Summary of Significant Accounting Policies
Restatement	Restatement As previously disclosed in the Explanatory Note to the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2020 (the “2020 10-K”), the Company restated its previously issued audited consolidated financial statements as of and for the years ended December 31, 2019 and 2018 and its unaudited interim condensed consolidated financial statements as of and for each of the quarterly periods ended March 31, 2020 and 2019, June 30, 2020 and 2019, September 30, 2020 and 2019 and December 31, 2019. Previously filed annual reports on Form 10-K and quarterly reports on Form 10-Q for the periods affected by the restatement have not been amended. Accordingly, investors should not rely upon the Company’s previously released financial statements for these periods and any earnings releases or other communications relating to these periods, and, for these periods, investors should rely solely on the financial statements and other financial data for the relevant periods included in the 2020 10-K. Commencing with our quarterly report on Form 10-Q for the quarterly period ended March 31, 2021, we are including in our quarterly reports for fiscal 2021 restated results for the corresponding interim periods of fiscal 2020.
Principles of Consolidation	Principles of Consolidation The unaudited interim condensed consolidated financial statements include the financial statements of the Company and its wholly-owned subsidiaries. Intercompany balances and transactions have been eliminated in consolidation. In addition, we include our share of the results of HyVia using the equity method based on our economic ownership interest and our ability to exercise significant influence over the operating and financial decisions of HyVia.
Interim Financial Statements	Interim Financial Statements The accompanying unaudited interim condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). In the opinion of management, all adjustments, which consist solely of normal recurring adjustments, necessary to present fairly, in accordance with U.S. generally accepted accounting principles (“GAAP”), the financial position, results of operations and cash flows for all periods presented, have been made. The results of operations for the interim periods presented are not necessarily indicative of the results that may be expected for the full year. Certain information and footnote disclosures normally included in annual consolidated financial statements prepared in accordance with GAAP have been condensed or omitted. These unaudited interim condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto included in the Company’s 2020 10-K. The information presented in the accompanying unaudited interim condensed consolidated balance sheets as of December 31, 2020 has been derived from the Company’s December 31, 2020 audited consolidated financial statements. There have been no changes in our accounting policies from those reported in our 2020 10-K, except for the adoption of 2020-06, as described in the Recently Adopted Accounting Guidance section. We have also expanded our accounting policy relating to cash equivalents, and available-for-sale securities as follows:
Cash Equivalents	Cash Equivalents The Company considers all highly-liquid debt securities with original maturities of three months or less to be cash equivalents. At June 30, 2021, cash equivalents consisted of commercial paper and U.S. Treasury securities with original maturities of three months or less, and money market funds. Due to their short-term nature, the carrying amounts reported in the unaudited interim condensed consolidated balance sheets approximate the fair value of cash and cash equivalents.
Available-for-sale securities	Available-for-sale securities Available-for-sale securities is comprised of commercial paper with original maturities greater than three months, U.S. Treasury securities, municipal debt, certificates of deposit and corporate bonds. We consider these securities to be Available-for-sale securities are recorded at fair value as of each balance sheet date. As of each balance sheet date, unrealized gains and losses, with the exception of credit related losses, are recorded to accumulated other comprehensive income. Any credit related losses are recognized as a credit loss allowance on the balance sheet with a corresponding adjustment to operations. Realized gains and losses are due to the sale and maturity of securities classified as available-for-sale and represent the net gain (loss) from accumulated other comprehensive income reclassifications for previously unrealized net gains on available-for-sale debt securities.
Equity securities	Equity securities Equity securities are comprised of fixed income and equity market index mutual funds. Equity securities are valued at fair value with changes in the fair value recognized in our unaudited interim condensed consolidated statement of operations. We consider these securities to be
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Adopted Accounting Guidance Other than the adoption of the accounting guidance mentioned i n our 2020 10-K and ASU 2020-06 On January 1, 2021, we early adopted ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40) using the modified retrospective approach. Consequently, the Company’s 3.75% Convertible Senior Notes due 2025 (the “3.75% Convertible Senior Notes”) is now accounted for as a single liability measured at its amortized cost. This accounting change removed the impact of recognizing the equity component of the Company’s convertible notes at issuance and the subsequent accounting impact of additional interest expense from debt discount amortization. Future interest expense of the convertible notes will be lower as a result of adoption of this guidance and net loss per share will be computed using the if-converted method for convertible instruments. The cumulative effect of the accounting change upon adoption on January 1, 2021 increased the carrying amount of the 3.75% Convertible Senior Notes by $120.6 million, reduced accumulated deficit by $9.6 million and reduced additional paid-in capital by $130.2 million. Recent Accounting Guidance Not Yet Effective All issued but not yet effective accounting and reporting standards as of June 30, 2021 are either not applicable to the Company or are not expected to have a material impact on the Company.

Extended Maintenance Contracts

Extended Maintenance Contracts (Tables)	6 Months Ended
Extended Maintenance Contracts (Tables)	Jun. 30, 2021
Extended Maintenance Contracts
Schedule of accrual for loss contracts	The following table shows the rollforward of balance in the accrual for loss contracts, including changes due to the passage of time, additions, and changes in estimates (in thousands): Six months ended Year ended June 30, 2021 December 31, 2020 Beginning Balance $ 24,013 $ 3,702 Provision for Loss Accrual 8,179 35,473 Released to Service Cost of Sales (3,780) (2,348) Released to Provision for Warrants — (12,814) Ending Balance $ 28,412 $ 24,013

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
Earnings Per Share (Tables)	Jun. 30, 2021
Earnings Per Share
Schedule of potential dilutive common shares	At June 30, 2021 2020 Stock options outstanding (1) 9,165,066 16,273,120 Restricted stock outstanding (2) 6,511,808 4,455,484 Common stock warrants (3) 83,518,821 110,573,392 Convertible Senior Notes (4) 39,170,766 72,872,730 Number of dilutive potential shares of common stock 138,366,461 204,174,726 (1) During the three months ended June 30, 2021 and 2020, the Company granted 117,500 and 89,649 stock options, respectively. During the six months ended June 30, 2021 and 2020, the Company granted 698,500 and 174,649 stock options, respectively. (2) During the three months ended June 30, 2021 and 2020, the Company granted 98,000 and 96,649 shares of restricted stock, respectively. During the six months ended June 30, 2021 and 2020, the Company granted 653,000 and 96,649 shares of restricted stock, respectively. (3) In April 2017, the Company issued a warrant to acquire up to 55,286,696 shares of the Company’s common stock as part of a transaction agreement with Amazon, subject to certain vesting events, as described in Note 12, “Warrant Transaction Agreements.” The warrant had been exercised with respect to 13,960,354 shares of the Company’s common stock as of June 30, 2021. In July 2017, the Company issued a warrant to acquire up to 55,286,696 shares of the Company’s common stock as part of a transaction agreement with Walmart, subject to certain vesting events, as described in Note 12, “Warrant Transaction Agreements.” The warrant had been exercised with respect to 13,094,217 shares of the Company’s common stock as of June 30, 2021. (4) In March 2018, the Company issued the 5.5% Convertible Senior Notes due 2023 (the “5.5% Convertible Senior Notes”). In September 2019, the Company issued the 7.5% Convertible Senior Note due 2023 (the “7.5% Convertible Senior Note”), which was fully converted into 16.0 million shares of common stock on July 1, 2020. In May 2020, the Company issued the 3.75% Convertible Senior Notes and repurchased $66.3 million of the 5.5% Convertible Senior Notes. In the fourth quarter of 2020, $33.5 million of the remaining 5.5% Convertible Senior Notes converted into 14.6 million shares of common stock. The remaining $160 thousand aggregate principal amount of the 5.5% Convertible Senior Notes were converted in January 2021. During the first quarter of 2021, $15.2 million of the 3.75% Convertible Senior Notes were converted, resulting in the issuance of 3,016,036 shares of common stock. There were no conversions in the second quarter of 2021.

Inventory (Tables)

Inventory (Tables)	6 Months Ended
Inventory (Tables)	Jun. 30, 2021
Inventory
Schedule of Inventory	Inventory as of June 30, 2021 and December 31, 2020 consisted of the following (in thousands): June 30, December 31, 2021 2020 Raw materials and supplies - production locations $ 131,932 $ 92,221 Raw materials and supplies - customer locations 14,096 12,405 Work-in-process 58,147 29,349 Finished goods 5,645 5,411 Inventory $ 209,820 $ 139,386

Equipment Related to Power Pu_2

Equipment Related to Power Purchase Agreements and Fuel Delivered to Customers, net (Tables)	6 Months Ended
	Jun. 30, 2021
Equipment Related to Power Purchase Agreements and Fuel Delivered to Customers, net
Equipment related to power purchase agreements and fuel delivered to customers, net	Equipment related to power purchase agreements and fuel delivered to customers, net at June 30, 2021 and December 31, 2020 consisted of the following (in thousands): June 30, December 31, 2021 2020 Equipment related to power purchase agreements and fuel delivered to customers $ 97,547 $ 92,736 Less: accumulated depreciation (18,629) (16,929) Equipment related to power purchase agreements and fuel delivered to customers, net 78,918 75,807

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	6 Months Ended
Property, Plant and Equipment (Tables)	Jun. 30, 2021
Property, Plant and Equipment
Schedule of Property plant and equipment	Property, plant and equipment at June 30, 2021 and December 31, 2020 consists of the following (in thousands): June 30, 2021 December 31, 2020 Land 1,165 1,165 Leasehold improvements $ 1,401 $ 1,121 Software, machinery and equipment 133,349 94,449 Property, plant, and equipment 135,915 96,735 Less: accumulated depreciation (25,440) (22,186) Property, plant, and equipment, net $ 110,475 $ 74,549

Intangible Assets and Goodwill

Intangible Assets and Goodwill (Tables)	6 Months Ended
Intangible Assets and Goodwill (Tables)	Jun. 30, 2021
Intangible Assets and Goodwill
Schedule of Intangible assets	The gross carrying amount and accumulated amortization of the Company’s acquired identifiable intangible assets as of June 30, 2021 were as follows (in thousands): Weighted Average Gross Carrying Accumulated Amortization Period Amount Amortization Total Acquired technology 10 years $ 13,150 $ (4,624) $ 8,526 Customer relationships, Non-compete agreements, Backlog & Trademark 6 years 890 (364) 526 In process research and development Indefinite 29,000 — 29,000 $ 43,040 $ (4,988) $ 38,052 The gross carrying amount and accumulated amortization of the Company’s acquired identifiable intangible assets as of December 31, 2020 were as follows (in thousands): Weighted Average Gross Carrying Accumulated Amortization Period Amount Amortization Total Acquired technology 10 years $ 13,697 $ (4,042) $ 9,655 Customer relationships, Non-compete agreements, Backlog & Trademark 6 years 890 (294) 596 In process research and development Indefinite 29,000 — 29,000 $ 43,587 $ (4,336) $ 39,251
Schedule of future amortization of intangible assets	The estimated amortization expense for subsequent years is as follows (in thousands): Remainder of 2021 $ 732 2022 1,463 2023 1,463 2024 1,442 2025 and thereafter 3,952 Total $ 9,052

Long-Term Debt (Tables)

Long-Term Debt (Tables)	6 Months Ended
Long-Term Debt (Tables)	Jun. 30, 2021
Long-Term Debt
Summary of principal payments of long term debt	As of June 30, 2021, the Term Loan Facility requires the principal balance as of each of the following dates not to exceed the following (in thousands): December 31, 2021 $ 127,317 December 31, 2022 93,321 December 31, 2023 62,920 December 31, 2024 33,692 December 31, 2025 —

Convertible Senior Notes (Table

Convertible Senior Notes (Tables) - 3.75% Convertible Senior Notes	6 Months Ended
	Jun. 30, 2021
Debt Instrument [Line Items]
Schedule of net proceeds from the Convertible Senior Notes	Amount (in thousands) Principal amount $ 212,463 Less initial purchasers' discount (6,374) Less cost of related capped calls (16,253) Less other issuance costs (617) Net proceeds $ 189,219
Schedule of Convertible Senior Notes	The 3.75% Convertible Senior Notes consisted of the following (in thousands): June 30, 2021 Principal amounts: Principal $ 197,278 Unamortized debt issuance costs (1) (5,267) Net carrying amount $ 192,011 1) Included in the unaudited interim condensed consolidated balance sheets within the 3.75% Convertible Senior Notes, net and amortized over the remaining life of the notes using the effective interest rate method.
Schedule of debt	June 30, 2021 Interest expense $ 1,850 Amortization of debt issuance costs 306 Total 2,156 Effective interest rate 4.50%

Warrant Transaction Agreements

Warrant Transaction Agreements (Tables)	6 Months Ended
Warrant Transaction Agreements (Tables)	Jun. 30, 2021
Warrant Transaction Agreements
Schedule of warranty assumptions	December 31, 2020 November 2, 2020 Risk-free interest rate 0.58% 0.58% Volatility 75.00% 75.00% Expected average term 6.26 6.42 Exercise price $13.81 $13.81 Stock price $33.91 $15.47

Revenue (Tables)

Revenue (Tables)	6 Months Ended
Revenue (Tables)	Jun. 30, 2021
Revenue
Schedule of disaggregation of revenue	The following table provides information about disaggregation of revenue (in thousands): Major products/services lines Three months ended June 30, Six months ended June 30, 2021 2020 2021 2020 Sales of fuel cell systems $ 59,169 $ 40,785 $ 85,588 $ 55,425 Sale of hydrogen installations and other infrastructure 40,109 6,961 60,462 12,789 Services performed on fuel cell systems and related infrastructure 5,675 6,236 11,720 12,757 Power Purchase Agreements 8,361 6,579 16,187 13,000 Fuel delivered to customers 11,121 7,372 22,248 14,705 Other 122 62 310 138 Net revenue $ 124,557 $ 67,995 $ 196,515 $ 108,814
Schedule of receivables, contract assets and contract liabilities from contracts with customers	The following table provides information about receivables, contract assets and contract liabilities from contracts with customers (in thousands): June 30, December 31, 2021 2020 Accounts receivable $ 91,359 $ 43,041 Contract assets 11,549 18,189 Contract liabilities 93,665 76,285
Schedule of changes in contract assets and the contract liabilities	Significant changes in the contract assets and the contract liabilities balances during the period are as follows (in thousands): Contract assets Six months ended June 30, 2021 Transferred to receivables from contract assets recognized at the beginning of the period $ (7,106) Revenue recognized and not billed as of the end of the period 466 Net change in contract assets (6,640) Contract liabilities Six months ended June 30, 2021 Increases due to cash received, net of amounts recognized as revenue during the period $ 49,628 Revenue recognized that was included in the contract liability balance as of the beginning of the period (32,248) Net change in contract liabilities $ 17,380
Schedule of Estimated future revenue	The following table includes estimated revenue included in the backlog expected to be recognized in the future (sales of fuel cell systems and hydrogen installations are expected to be recognized as revenue within one year; sales services five June 30, 2021 Sales of fuel cell systems $ 55,348 Sale of hydrogen installations and other infrastructure 52,193 Services performed on fuel cell systems and related infrastructure 103,505 Power Purchase Agreements 196,903 Fuel delivered to customers 63,632 Other rental income 2,504 Total estimated future revenue $ 474,085

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
Fair Value Measurements (Tables)	Jun. 30, 2021
Fair Value Measurements
Schedule of assets and liabilities measured at fair value on a recurring basis	Assets and liabilities measured at fair value on a recurring basis are summarized below (in thousands): As of June 30, 2021 Carrying Fair Fair Value Measurements Amount Value Level 1 Level 2 Level 3 Assets Cash equivalents (1) $ 141,313 $ 141,313 $ 87,573 $ 53,740 $ — Corporate bonds 705,084 705,084 — 705,084 — Commercial paper 329,722 329,722 — 329,722 — U.S. Treasuries 170,477 170,477 170,477 — — Municipal debt 9,984 9,984 — 9,984 — Certificates of deposit 27,454 27,454 — 27,454 — Equity securities 120,302 120,302 120,302 — — Liabilities Contingent consideration 9,990 9,990 — — 9,990 Convertible senior notes 192,011 1,320,194 — 1,320,194 — Long-term debt 160,484 160,484 — — 160,484 Finance obligations 195,805 195,805 — — 195,805 As of December 31, 2020 Carrying Fair Fair Value Measurements Amount Value Level 1 Level 2 Level 3 Liabilities Contingent consideration 9,760 9,760 — — 9,760 Convertible senior notes 85,640 1,272,766 — 1,272,766 — Long-term debt 175,402 175,402 — — 175,402 Finance obligations 181,553 181,553 — — 181,553 (1) Included in “Cash and cash equivalents” in our unaudited interim condensed consolidated balance sheets as of June 30, 2021.

Operating and Finance Lease L_2

Operating and Finance Lease Liabilities (Tables)	6 Months Ended
Operating and Finance Lease Liabilities (Tables)	Jun. 30, 2021
Operating and Finance Lease Liabilities
Schedule of future minimum lease payments under operating leases	Future minimum lease payments under operating and finance leases (with initial or remaining lease terms in excess of one year) as of June 30, 2021 were as follows (in thousands): Finance Total Operating Lease Lease Lease Liability Liability Liabilities Remainder of 2021 $ 17,298 $ 1,826 $ 19,124 2022 34,579 3,731 38,310 2023 34,636 3,708 38,344 2024 34,636 3,715 38,351 2025 and thereafter 73,276 4,921 78,197 Total future minimum payments 194,425 17,901 212,326 Less imputed interest (52,307) (2,793) (55,100) Total $ 142,118 $ 15,108 $ 157,226
Schedule of operating leases other information	Six months ended Six months ended June 30, 2021 June 30, 2020 Cash payments (in thousands) $ 16,081 $ 9,674 Weighted average remaining lease term (years) 5.82 4.34 Weighted average discount rate 11.4% 12.1%
Schedule of finance leases other information	Six months ended Six months ended June 30, 2021 June 30, 2020 Cash payments (in thousands) $ 1,166 $ 132 Weighted average remaining lease term (years) 4.86 6.74 Weighted average discount rate 6.9% 9.6%

Finance Obligations (Tables)

Finance Obligations (Tables)	6 Months Ended
Finance Obligations (Tables)	Jun. 30, 2021
Sale Leaseback Transaction [Line Items]
Schedule of finance leases other information	Six months ended Six months ended June 30, 2021 June 30, 2020 Cash payments (in thousands) $ 1,166 $ 132 Weighted average remaining lease term (years) 4.86 6.74 Weighted average discount rate 6.9% 9.6%
Finance obligation
Sale Leaseback Transaction [Line Items]
Schedule of future minimum lease payments under finance obligations	Future minimum payments under finance obligations notes above as of June 30, 2021 were as follows (in thousands): Total Sale of Future Sale/leaseback Finance revenue - debt financings Obligations Remainder of 2021 $ 23,525 $ 4,212 $ 27,737 2022 46,165 4,975 51,140 2023 46,165 3,148 49,313 2024 46,165 16,154 62,319 2025 and thereafter 72,708 — 72,708 Total future minimum payments 234,728 28,489 263,217 Less imputed interest (58,461) (8,951) (67,412) Total $ 176,267 $ 19,538 $ 195,805
Schedule of finance leases other information	Six months ended Six months ended June 30, 2021 June 30, 2020 Cash payments (in thousands) $ 26,508 $ 20,148 Weighted average remaining term (years) 4.9 4.3 Weighted average discount rate 11.3% 11.2%

Investments (Tables)

Investments (Tables)	6 Months Ended
Investments (Tables)	Jun. 30, 2021
Investments
Schedule of gross unrealized gains and losses, and the amortized cost, allowance for credit losses, and fair value of those investments classified as available-for-sale	The amortized cost, gross unrealized gains and losses, fair value of those investments classified as available-for-sale, and allowance for credit losses at June 30, 2021 are summarized as follows (in thousands): Amortized Gross Gross Fair Allowance for Cost Unrealized Gains Unrealized Losses Value Credit Losses Corporate bonds $ 707,022 $ 51 $ (1,989) $ 705,084 — Commercial paper 329,471 253 (2) 329,722 — Certificates of deposit 27,460 — (6) 27,454 — U.S. Treasuries 170,672 — (195) 170,477 — Municipal debt 9,993 — (9) 9,984 — Total $ 1,244,618 $ 304 $ (2,201) $ 1,242,721 $ —
Schedule of investments classified as equity securities	The cost, gross unrealized gains and losses, and fair value of those investments classified as equity securities at June 30, 2021 are summarized as follows (in thousands): June 30, 2021 Gross Gross Fair Cost Unrealized Gains Unrealized Losses Value Fixed income mutual funds $ 89,962 $ 17 $ (81) $ 89,898 Exchange traded mutual funds 30,016 388 — 30,404 Total $ 119,978 $ 405 $ (81) $ 120,302
Schedule of the amortized cost and fair value of investments classified as available-for-sale, by contractual maturity	A summary of the amortized cost and fair value of investments classified as available-for-sale, by contractual maturity, as of June 30, 2021 is as follows (in thousands): June 30, 2021 Amortized Fair Maturity: Cost Value Within one year $ 717,531 $ 717,285 After one through five years 527,087 525,436 Total $ 1,244,618 $ 1,242,721

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	6 Months Ended
Employee Benefit Plans (Tables)	Jun. 30, 2021
Employee Benefit Plans
Assumptions made for the purpose of estimating fair value	June 30, June 30, 2021 2020 Expected term of options (years) 5 6 Risk free interest rate 0.61% - 1.04% 0.45% - 1.37% Volatility 72.46% - 73.69% 64.19% - 64.80%
Schedule of Share-based Compensation, Stock Options, Activity	A summary of stock option activity for the six months ended June 30, 2021 is as follows (in thousands except share amounts): Weighted Weighted Average Average Remaining Aggregate Exercise Contractual Intrinsic Shares Price Terms Value Options outstanding at December 31, 2020 10,284,498 $ 5.78 7.8 $ 289,316 Granted 698,500 46.82 — — Exercised (1,812,099) 2.65 — — Forfeited (5,833) 6.78 — — Expired — — — — Options outstanding at June 30, 2021 9,165,066 $ 9.51 7.9 $ 226,164 Options exercisable at June 30, 2021 2,523,341 2.17 5.6 80,808 Options unvested at June 30, 2021 6,641,725 $ 12.30 8.7 $ 145,356
Nonvested Restricted Stock Shares Activity	A summary of restricted stock activity for the year ended June 30, 2021 is as follows (in thousands except share amounts): Aggregate Intrinsic Shares Value Unvested restricted stock at December 31, 2020 5,874,642 $ — Granted 653,000 — Vested (149,650) — Forfeited (5,833) — Unvested restricted stock at June 30, 2021 6,372,159 $ 217,864

Nature of Operations - Descript

Nature of Operations - Description Of Business (Details) - HyVia	Jun. 30, 2021
Plug Power France
Description of Business
Ownership interest percentage	50.00%
Renault
Description of Business
Ownership interest percentage	50.00%

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021	Jan. 01, 2021	Dec. 31, 2020	May 31, 2020	May 29, 2020	May 18, 2020
Summary of Significant Accounting Policies
Convertible Debt			$ 120,600
Accumulated deficit	$ (2,097,319)		9,600	$ (1,946,488)
Additional paid-in capital	$ 6,962,720		$ 130,200	$ 3,446,650
Interest rate (as a percent)			3.75%
3.75% Convertible Senior Notes
Summary of Significant Accounting Policies
Interest rate (as a percent)	3.75%	3.75%			3.75%	3.75%	3.75%

Extended Maintenance Contract_2

Extended Maintenance Contracts (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Accrual for loss contracts
Beginning Balance	$ 24,013	$ 3,702
Provision for Loss Accrual	8,179	35,473
Released to Service Cost of Sales	(3,780)	(2,348)
Released to Provision for Warrants		(12,814)
Ending Balance	$ 28,412	$ 24,013

Earnings Per Share - Dilutive P

Earnings Per Share - Dilutive Potential Common Shares (Details) - USD ($) $ in Thousands	Jan. 07, 2021	Jul. 01, 2020	Jul. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Jan. 31, 2021	Jan. 01, 2021	May 31, 2020	May 29, 2020	May 18, 2020	Sep. 30, 2019	Mar. 31, 2018	Jul. 20, 2017	Apr. 04, 2017
Earnings Per Share
Number of dilutive potential common stock								138,366,461	204,174,726
Stock options granted								698,500	174,649
Number of warrants exercised (in shares)					16,489,014
Conversion of notes through common stock issuance		16,000,000
Interest rate (as a percent)											3.75%
3.75% Convertible Senior Notes
Earnings Per Share
Principal amount				$ 197,278				$ 197,278				$ 212,463	$ 12,500	$ 200,000
Conversion of notes through common stock issuance					3,016,036			3,000,000
Convertible senior notes					$ 15,200
Interest rate (as a percent)				3.75%	3.75%			3.75%				3.75%	3.75%	3.75%
7.5% Convertible Senior Note
Earnings Per Share
Interest rate (as a percent)															7.50%
5.5% Convertible Senior Notes
Earnings Per Share
Principal amount	$ 160					$ 33,500								$ 100,000		$ 100,000
Outstanding balance										$ 160
Conversion of notes through common stock issuance	69,808					14,600,000
Debt Instrument, Repurchased Face Amount												$ 66,300
Interest rate (as a percent)	5.50%			5.50%		5.50%	5.50%	5.50%	5.50%	5.50%		5.50%		5.50%		5.50%
Stock options
Earnings Per Share
Stock options granted								698,500
Warrant Transaction Agreements
Earnings Per Share
Shares of common stock that can be purchased from warrants issued (in shares)																		55,286,696
Number of warrants exercised (in shares)			3,501,640	4,745,905	9,214,449			13,960,354
Warrants issued with the Walmart Stores, Inc transaction agreement
Earnings Per Share
Shares of common stock that can be purchased from warrants issued (in shares)																	55,286,696
Number of warrants exercised (in shares)				0	7,274,565	5,819,652		13,094,217
Stock options
Earnings Per Share
Number of dilutive potential common stock								9,165,066	16,273,120
Stock options granted				117,500			89,649	698,500	174,649
Restricted stock outstanding
Earnings Per Share
Number of dilutive potential common stock								6,511,808	4,455,484
Stock options granted				98,000			96,649	653,000	96,649
Warrants
Earnings Per Share
Number of dilutive potential common stock								83,518,821	110,573,392
Convertible senior notes
Earnings Per Share
Number of dilutive potential common stock								39,170,766	72,872,730

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Inventory
Raw materials and supplies - production locations	$ 131,932	$ 92,221
Raw materials and supplies - customer locations	14,096	12,405
Work-in-process	58,147	29,349
Finished goods	5,645	5,411
Inventory	$ 209,820	$ 139,386

Equipment Related to Power Pu_3

Equipment Related to Power Purchase Agreements and Fuel Delivered to Customers, net (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Equipment Related to Power Purchase Agreements and Fuel Delivered to Customers, net
Lessor property and equipment related to power purchase agreements	$ 97,547	$ 92,736
Less: accumulated depreciation	(18,629)	(16,929)
Lessor property and equipment related to power purchase agreements, net	$ 78,918	$ 75,807

Equipment Related to Power Pu_4

Equipment Related to Power Purchase Agreements and Fuel Delivered to Customers, net - Future minimum lease payments (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2021USD ($)	Jun. 30, 2021USD ($)
Lessor, Lease, Description [Line Items]
Depreciation expense	$ 2	$ 3.8
Minimum
Lessor, Lease, Description [Line Items]
Lease term	1 year	1 year
Maximum
Lessor, Lease, Description [Line Items]
Lease term	10 years	10 years

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Property, plant and equipment
Property, plant, and equipment, gross	$ 135,915		$ 135,915		$ 96,735
Less: accumulated depreciation	(25,440)		(25,440)		(22,186)
Property, plant, and equipment, net	110,475		110,475		74,549
Depreciation expense	1,600	$ 900	3,300	$ 1,800
Land
Property, plant and equipment
Property, plant, and equipment, gross	1,165		1,165		1,165
Leasehold Improvements
Property, plant and equipment
Property, plant, and equipment, gross	1,401		1,401		1,121
Software, machinery and equipment
Property, plant and equipment
Property, plant, and equipment, gross	$ 133,349		$ 133,349		$ 94,449

Intangible Assets and Goodwil_2

Intangible Assets and Goodwill - Gross Carrying Amount (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Gross carrying amount and accumulated amortization of acquired identifiable intangible assets
Gross Carrying Amount	$ 43,040	$ 43,587
Accumulated Amortization	(4,988)	(4,336)
Total	38,052	39,251
Goodwill	72,083	72,387
Translation loss on goodwill		(304)
Goodwill impairments	0	0
In process R&D
Gross carrying amount and accumulated amortization of acquired identifiable intangible assets
Gross Carrying Amount	29,000	29,000
Total	$ 29,000	$ 29,000
Acquired technology
Gross carrying amount and accumulated amortization of acquired identifiable intangible assets
Weighted Average Amortization Period	10 years	10 years
Gross Carrying Amount	$ 13,150	$ 13,697
Accumulated Amortization	(4,624)	(4,042)
Total	$ 8,526	$ 9,655
Customer relationships, Backlog & Trademark
Gross carrying amount and accumulated amortization of acquired identifiable intangible assets
Weighted Average Amortization Period	6 years	6 years
Gross Carrying Amount	$ 890	$ 890
Accumulated Amortization	(364)	(294)
Total	$ 526	$ 596

Intangible Assets and Goodwil_3

Intangible Assets and Goodwill - Estimated Amortization Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Intangible Assets and Goodwill
Amortization of Intangible Assets	$ 400	$ 200	$ 730	$ 398
Estimated amortization expense
Remainder of 2021	732		732
2022	1,463		1,463
2023	1,463		1,463
2024	1,442		1,442
2025 and thereafter	3,952		3,952
Total	$ 9,052		$ 9,052

Long-Term Debt (Details)

Long-Term Debt (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
Long-Term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Jan. 01, 2021	Dec. 31, 2019	Mar. 31, 2019
Long-Term Debt
Interest rate (as a percent)					3.75%
Loss on extinguishment of debt	$ 13,222		$ 13,222
Percent of securities in foreign subsidiaries guaranteed to secure debt		65.00%
Principal payments of long term debt
December 31, 2021		$ 127,317
December 31, 2022		93,321
December 31, 2023		62,920
December 31, 2024		33,692
Secured term loan facility \| Loan and security agreement
Long-Term Debt
Borrowing				$ 100,000
Interest rate (as a percent)				9.50%		12.00%
Term Loan facility
Principal payments of long term debt
Incremental term loan		150,800
Term Loan facility \| United Hydrogen Group Inc
Principal payments of long term debt
Incremental term loan		$ 10,000
Generate Lending, LLC \| Secured term loan facility \| Loan and security agreement
Long-Term Debt
Loan Amount							$ 100,000

Convertible Senior Notes - Net

Convertible Senior Notes - Net proceeds (Details) $ / shares in Units, $ in Thousands	Jan. 07, 2021USD ($)shares	Jul. 01, 2020shares	May 18, 2020USD ($)D$ / shares	Nov. 30, 2020$ / sharesshares	Aug. 31, 2020$ / sharesshares	May 31, 2020USD ($)shares	Mar. 31, 2021USD ($)shares	Dec. 31, 2020USD ($)shares	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)$ / sharesshares	Jun. 30, 2020USD ($)	Jan. 31, 2021USD ($)	Jan. 01, 2021	May 29, 2020USD ($)	Sep. 30, 2019	Mar. 31, 2018USD ($)
Convertible Senior Notes
Interest rate (as a percent)													3.75%
Net proceeds										$ 32,159	$ 27,678
Aggregate consideration											90,238
Conversion of convertible senior notes to common stock										15,345
Conversion of notes through common stock issuance \| shares		16,000,000
Convertible senior note											441
Proceeds from issuance of convertible senior notes, net											205,100
Gain on extinguishment of debt									$ 13,222		$ 13,222
Closing price of the company's stock \| $ / shares				$ 22.25	$ 10.25
Common stock shares issued \| shares				43,700,000	35,276,250
3.75% Convertible Senior Notes
Convertible Senior Notes
Principal amount			$ 200,000			$ 212,463				$ 197,278				$ 12,500
Interest rate (as a percent)			3.75%			3.75%	3.75%			3.75%				3.75%
Net proceeds						$ 189,219
Conversion of notes through common stock issuance \| shares							3,016,036			3,000,000
Convertible senior notes							$ 15,200
Maturity principal amount			$ 1
Conversion rates for the notes (in shares)			198.6196
Conversion price, per share \| $ / shares			$ 5.03
Convertible senior note										$ 15,200
Trading days \| D			20
Consecutive trading days \| D			30
Conversion price (as a percent)			130.00%
Number of business days			5 days
Number of consecutive trading days			5 days
Principal amount (as a percent)			98.00%
Percentage of principal amount to be redeemed			100.00%
Effective interest rate (as a percent)										4.50%
Transaction costs for issuance			$ 7,000
Initial purchasers' discount			6,400			6,374
Other issuance costs			$ 600			$ 617
Closing price of the company's stock \| $ / shares										$ 34.19
Fair value of convertible senior notes										$ 1,300,000
3.75% Convertible Senior Notes \| Minimum
Convertible Senior Notes
Redemption notice days			1 day
3.75% Convertible Senior Notes \| Maximum
Convertible Senior Notes
Redemption notice days			3 days
7.5% Convertible Senior Note
Convertible Senior Notes
Interest rate (as a percent)															7.50%
5.5% Convertible Senior Notes
Convertible Senior Notes
Principal amount	$ 160		$ 100,000					$ 33,500								$ 100,000
Interest rate (as a percent)	5.50%		5.50%			5.50%		5.50%	5.50%	5.50%	5.50%	5.50%				5.50%
Repurchase of convertible senior notes \| shares						9,400,000
Aggregate repurchase of debt						$ 128,900
Aggregate consideration						90,200
Conversion of notes through common stock issuance \| shares	69,808							14,600,000
Long-term borrowings												$ 160
Maturity principal amount						66,300
Gain on early debt extinguishment						$ 13,200
Gain on extinguishment of debt								$ 4,500

Convertible Senior Notes - Conv

Convertible Senior Notes - Conversion (Details) - USD ($) $ in Thousands	May 18, 2020	May 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Jan. 07, 2021	Dec. 31, 2020	May 29, 2020	Mar. 31, 2018
Convertible Senior Notes
Net proceeds			$ 32,159	$ 27,678
5.5% Convertible Senior Notes
Convertible Senior Notes
Principal amount	$ 100,000				$ 160	$ 33,500		$ 100,000
3.75% Convertible Senior Notes
Convertible Senior Notes
Principal amount	200,000	$ 212,463	$ 197,278				$ 12,500
Less initial purchasers' discount	(6,400)	(6,374)
Less cost of related capped calls		(16,253)
Less other issuance costs	$ (600)	(617)
Net proceeds		$ 189,219

Convertible Senior Notes (Detai

Convertible Senior Notes (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Jan. 07, 2021	Dec. 31, 2020	May 31, 2020	May 29, 2020	May 18, 2020	Mar. 31, 2018
Convertible Senior Notes
Net carrying amount	$ 192,011		$ 85,640
3.75% Convertible Senior Notes
Convertible Senior Notes
Principal amount	197,278			$ 212,463	$ 12,500	$ 200,000
Unamortized debt issuance costs	(5,267)
Net carrying amount	$ 192,011
5.5% Convertible Senior Notes
Convertible Senior Notes
Principal amount		$ 160	$ 33,500			$ 100,000	$ 100,000

Convertible Senior Notes - Expe

Convertible Senior Notes - Expenses and Interest (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Debt Instrument [Line Items]
Amortization of debt issuance costs and discount on convertible senior notes	$ 1,726	$ 6,528
3.75% Convertible Senior Notes
Debt Instrument [Line Items]
Interest expense	1,850
Amortization of debt issuance costs and discount on convertible senior notes	306
Total	$ 2,156
Effective interest rate (as a percent)	4.50%

Convertible Senior Notes - Capp

Convertible Senior Notes - Capped Call and Common Stock Forward (Details) - USD ($) $ / shares in Units, $ in Thousands	May 18, 2020	Nov. 30, 2020	Aug. 31, 2020	May 31, 2020	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2021	Jan. 31, 2021	Jan. 07, 2021	Jan. 01, 2021	Jun. 30, 2020	May 29, 2020	Sep. 30, 2019	Mar. 31, 2018
Capped Call and Common Stock Forward
Interest rate (as a percent)											3.75%
Share Price		$ 22.25	$ 10.25
Common stock shares issued		43,700,000	35,276,250
Common Stock Forward
Capped Call and Common Stock Forward
Common stock shares issued					2,200,000	5,900,000	4,400,000
Net cost incurred								$ 27,500
3.75% Convertible Senior Notes
Capped Call and Common Stock Forward
Interest rate (as a percent)	3.75%			3.75%	3.75%	3.75%		3.75%					3.75%
Principal amount	$ 200,000			$ 212,463	$ 197,278			$ 197,278					$ 12,500
Share Price					$ 34.19			$ 34.19
Percentage of principal amount to be redeemed	100.00%
3.75% Convertible Senior Notes \| Capped Call
Capped Call and Common Stock Forward
Capped call options amount	$ 16,200
Cap price	$ 6.7560
Premium (as a percent)	60.00%
Share Price	$ 4.11
5.5% Convertible Senior Notes
Capped Call and Common Stock Forward
Interest rate (as a percent)	5.50%			5.50%	5.50%		5.50%	5.50%	5.50%	5.50%		5.50%			5.50%
Principal amount	$ 100,000						$ 33,500			$ 160					$ 100,000
5.5% Convertible Senior Notes \| Capped Call
Capped Call and Common Stock Forward
Capped call options amount				$ 16,000
Recorded in additional paid-in capital				$ 24,200
Percentage of principal amount to be redeemed				100.00%
5.5% Convertible Senior Notes \| Common Stock Forward
Capped Call and Common Stock Forward
Common stock shares issued								14,397,906
7.5% Convertible Senior Note
Capped Call and Common Stock Forward
Interest rate (as a percent)														7.50%

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock and Warrants (Details) $ / shares in Units, $ in Thousands	Apr. 13, 2020USD ($)	Feb. 28, 2021USD ($)$ / sharesshares	Nov. 30, 2020USD ($)$ / sharesshares	Aug. 31, 2020USD ($)$ / sharesshares	Feb. 28, 2021USD ($)$ / sharesshares	Jun. 30, 2021$ / sharesshares	Mar. 31, 2021shares	Jun. 30, 2021USD ($)item$ / sharesshares	Jun. 30, 2020USD ($)	Dec. 31, 2020$ / sharesshares	Dec. 31, 2017shares
Stockholders' equity
Preferred stock, Shares authorized						5,000,000		5,000,000
Preferred stock, par value \| $ / shares						$ 0.01		$ 0.01
Net proceeds from shares of common stock sold \| $			$ 927,300	$ 344,400				$ 3,587,825	$ (269)
Common Stock Shares, Outstanding						570,922,157		570,922,157		458,051,401
Common Stock, Shares, Issued						586,848,225		586,848,225		473,977,469
Common stock, par value (in dollars per share) \| $ / shares						$ 0.01		$ 0.01		$ 0.01
Number of votes per share \| item								1
Common stock shares issued			43,700,000	35,276,250
Share price (in dollars per share) \| $ / shares			$ 22.25	$ 10.25
Number of warrants exercised (in shares)							16,489,014
Proceeds from exercise of warrants, net of transaction costs \| $								$ 15,450
Series A Junior Participating Cumulative Preferred Stock
Stockholders' equity
Preferred stock, par value \| $ / shares						$ 0.01		$ 0.01
Common Stock Shares, Outstanding						0		0		0
SK Holdings Co LTD
Stockholders' equity
Net proceeds from shares of common stock sold \| $		$ 1,600,000
Common stock shares issued		54,966,188
Per share price of shares of common stock \| $ / shares		$ 29.2893			$ 29.2893
At Market Issuance Sales Agreement
Stockholders' equity
Authorized amount \| $	$ 75,000
Public Offerings
Stockholders' equity
Net proceeds from shares of common stock sold \| $					$ 1,800,000
Common stock shares issued					32,200,000
Share price (in dollars per share) \| $ / shares		$ 65			$ 65
Warrant Issued With Amazon And Walmart Stores Inc Transaction Agreement In 2017
Stockholders' equity
Number of warrants exercised (in shares)						4,745,905
Number of warrants were vested and exercisable								68,380,913		68,380,913
Maximum \| Warrant Issued With Amazon And Walmart Stores Inc Transaction Agreement In 2017
Stockholders' equity
Class of Warrant or Right Issued											110,573,392

Warrant Transaction Agreement_2

Warrant Transaction Agreements - Amazon.com, Inc. Transaction Agreement (Details) $ / shares in Units, $ in Thousands	Dec. 31, 2020USD ($)$ / sharesshares	Nov. 02, 2020USD ($)installment$ / sharesshares	Jan. 01, 2019USD ($)installmentshares	Apr. 04, 2017USD ($)shares	Jul. 31, 2021shares	Jun. 30, 2021USD ($)$ / sharesshares	Mar. 31, 2021shares	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)$ / sharesshares	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Class of Warrant or Right [Line Items]
Number of warrants exercised (in shares) \| shares							16,489,014
Selling, general and administrative						$ 38,652		$ 21,644	$ 64,231	$ 32,753
Provision for loss contracts related to service									(4,399)	(277)
Risk-free interest rate	0.58%	0.58%									0.58%
Volatility	75.00%	75.00%									75.00%
Expected average term		6 years 5 months 1 day									6 years 3 months 3 days
Exercise price \| $ / shares	$ 13.81	$ 13.81									$ 13.81
Stock price \| $ / shares	$ 33.91	15.47									$ 33.91
Warrant Transaction Agreements
Class of Warrant or Right [Line Items]
Shares of common stock that can be purchased from warrants issued (in shares) \| shares				55,286,696
Reduction in revenue						$ 105		$ 3,400	$ 209	$ 4,700
Number of warrants exercised (in shares) \| shares					3,501,640	4,745,905	9,214,449		13,960,354
Warrant shares vested (in shares) \| shares	55,286,696										55,286,696
Fair value of warrants per share \| $ / shares		$ 10.57									$ 26.95
Tranche one of warrants issued with the Amazon.com, Inc transaction agreement
Class of Warrant or Right [Line Items]
Shares of common stock that can be purchased from warrants issued (in shares) \| shares				5,819,652
Cash payments to be received under agreement				$ 600,000
Selling, general and administrative				$ 6,700
Exercise price calculation									$1.1893
Tranche two of warrants issued with the Amazon.com, Inc. Transaction Agreement
Class of Warrant or Right [Line Items]
Cash payments to be received under agreement			$ 50,000
Reduction in revenue											$ 9,000	$ 4,100	$ 9,800
Warrant shares vested (in shares) \| shares			29,098,260
Number of installments \| installment			4
Tranche two of warrants issued with the Amazon.com, Inc. Transaction Agreement \| Maximum
Class of Warrant or Right [Line Items]
Cash payments to be received under agreement			$ 200,000
Tranche three of warrants issued with the Amazon.com, Inc. Transaction Agreement
Class of Warrant or Right [Line Items]
Cash payments to be received under agreement		$ 50,000
Reduction in revenue	$ 399,700										24,100
Warrant shares vested (in shares) \| shares		20,368,784
Number of installments \| installment		8
Exercise price of warrants (in dollars per share) \| $ / shares						$ 13.81			$ 13.81
Fair value of warrants per share \| $ / shares		$ 10.57
Warrant percentage weighted average share price									90.00%
Tranche three of warrants issued with the Amazon.com, Inc. Transaction Agreement \| Maximum
Class of Warrant or Right [Line Items]
Cash payments to be received under agreement		$ 400,000
Warrant Issued With Amazon
Class of Warrant or Right [Line Items]
Reduction in revenue											$ 399,700
Warrant shares vested (in shares) \| shares	5,354,905	12,730,490									5,354,905
Provision for loss contracts related to service											$ 12,800

Warrant Transaction Agreement_3

Warrant Transaction Agreements - Walmart Stores, Inc. Transaction Agreement (Details) $ / shares in Units, $ in Millions	Jul. 20, 2017USD ($)installment$ / sharesshares	Jun. 30, 2021USD ($)shares	Mar. 31, 2021shares	Dec. 31, 2020shares	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)shares	Jun. 30, 2020USD ($)
Warrant Transaction Agreements
Number of warrants exercised (in shares)			16,489,014
Warrants issued with the Walmart Stores, Inc transaction agreement
Warrant Transaction Agreements
Shares of common stock that can be purchased from warrants issued (in shares)	55,286,696
Reduction in revenue \| $		$ 1.6			$ 1	$ 3.2	$ 1.9
Cash payments to be received under agreement \| $	$ 200
Warrant shares vested (in shares)		13,094,217		13,094,217		13,094,217
Exercise price calculation	The exercise price of the third tranche of Walmart Warrant Shares will be an amount per share equal to ninety percent (90%) of the 30-day volume weighted average share price of the common stock as of the final vesting date of the second tranche of Walmart Warrant Shares, provided that, with limited exceptions, the exercise price for the third tranche will be no lower than $1.1893
Number of warrants exercised (in shares)		0	7,274,565	5,819,652		13,094,217
Tranche one of warrants issued with the Walmart Stores Inc transaction agreement
Warrant Transaction Agreements
Reduction in revenue \| $	$ 10.9
Warrant shares vested (in shares)	5,819,652
Exercise price of warrants (in dollars per share) \| $ / shares	$ 2.1231
Tranche two of warrants issued with the Walmart Stores, Inc. Transaction Agreement
Warrant Transaction Agreements
Cash payments to be received under agreement \| $	$ 50
Warrant shares vested (in shares)	29,098,260
Number of installments \| installment	4
Number of shares per installment	7,274,565
Tranche three of warrants issued with the Walmart Stores, Inc. Transaction Agreement
Warrant Transaction Agreements
Shares of common stock that can be purchased from warrants issued (in shares)	20,368,784
Cash payments to be received under agreement \| $	$ 50
Number of installments \| installment	8
Number of shares per installment	2,546,098
Maximum \| Warrants issued with the Walmart Stores, Inc transaction agreement
Warrant Transaction Agreements
Cash payments to be received under agreement \| $	$ 600
Maximum \| Tranche two of warrants issued with the Walmart Stores, Inc. Transaction Agreement
Warrant Transaction Agreements
Cash payments to be received under agreement \| $	200
Maximum \| Tranche three of warrants issued with the Walmart Stores, Inc. Transaction Agreement
Warrant Transaction Agreements
Cash payments to be received under agreement \| $	$ 400

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue
Net revenue	$ 124,557	$ 67,995	$ 196,515	$ 108,814
Sales of fuel cell systems
Revenue
Net revenue	59,169	40,785	85,588	55,425
Sale of hydrogen installations and other infrastructure
Revenue
Net revenue	40,109	6,961	60,462	12,789
Services performed on fuel cell systems and related infrastructure
Revenue
Net revenue	5,675	6,236	11,720	12,757
Power Purchase Agreements
Revenue
Net revenue	8,361	6,579	16,187	13,000
Fuel delivered to customers
Revenue
Net revenue	11,121	7,372	22,248	14,705
Other
Revenue
Net revenue	$ 122	$ 62	$ 310	$ 138

Revenue - Contract balances (De

Revenue - Contract balances (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Revenue
Accounts receivable	$ 91,359	$ 43,041
Contract assets	11,549	18,189
Contract liabilities	93,665	76,285
Other Current Liabilities
Revenue
Contract liabilities	21,400	20,100
Sales of fuel cell systems
Revenue
Contract liabilities	$ 72,300	$ 56,200

Revenue - Changes in contract a

Revenue - Changes in contract assets and contract liabilities (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Contract assets
Transferred to receivables from contract assets recognized at the beginning of the period	$ (7,106)
Revenue recognized and not billed as of the end of the period	466
Net change in contract assets	(6,640)
Contract liabilities
Increases due to cash received, net of amounts recognized as revenue during the period	49,628
Revenue recognized that was included in the contract liability balance as of the beginning of the period	(32,248)
Net change in contract liabilities	$ 17,380

Revenue - Estimated future reve

Revenue - Estimated future revenue (Details) $ in Thousands	6 Months Ended
Revenue - Estimated future revenue (Details) $ in Thousands	Jun. 30, 2021USD ($)
Revenue
Total estimated future revenue	$ 474,085
Sales of fuel cell systems
Revenue
Total estimated future revenue	55,348
Sale of hydrogen installations and other infrastructure
Revenue
Total estimated future revenue	52,193
Services performed on fuel cell systems and related infrastructure
Revenue
Total estimated future revenue	103,505
Power Purchase Agreements
Revenue
Total estimated future revenue	196,903
Fuel delivered to customers
Revenue
Total estimated future revenue	63,632
Other
Revenue
Total estimated future revenue	$ 2,504
Maximum \| Sales of fuel cell systems
Revenue
Duration of estimated revenue expected to be recognized in future (in years)	1 year
Maximum \| Services performed on fuel cell systems and related infrastructure
Revenue
Duration of estimated revenue expected to be recognized in future (in years)	7 years
Maximum \| Power Purchase Agreements
Revenue
Duration of estimated revenue expected to be recognized in future (in years)	7 years
Minimum \| Services performed on fuel cell systems and related infrastructure
Revenue
Duration of estimated revenue expected to be recognized in future (in years)	5 years
Minimum \| Power Purchase Agreements
Revenue
Duration of estimated revenue expected to be recognized in future (in years)	5 years

Revenue - Others (Details)

Revenue - Others (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Revenue
Capitalized contract costs	$ 1.2	$ 1.5

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Jan. 31, 2021	Jan. 07, 2021	Jan. 01, 2021	Dec. 31, 2020	May 31, 2020	May 29, 2020	May 18, 2020	Mar. 31, 2018
Income tax benefit	$ 0	$ 17,371	$ 0	$ 17,371
Including a benefit		$ 12,200		12,200
Interest rate (as a percent)								3.75%
Giner ELX, Inc
Income tax benefit				$ 5,200
3.75% Convertible Senior Notes
Interest rate (as a percent)	3.75%		3.75%		3.75%					3.75%	3.75%	3.75%
5.5% Convertible Senior Notes
Interest rate (as a percent)	5.50%	5.50%	5.50%	5.50%		5.50%	5.50%		5.50%	5.50%		5.50%	5.50%

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Fair Value Measurements
Assets, transfers from level 1 to level 2	$ 0
Assets, transfers from level 2 to level 1	0
Asset transfer into Level 3	0
Asset transfer out of Level 3	0
Liabilities, transfers from level 1 to level 2	0
Liabilities, transfers from level 2 to level 1	0
Liabilities transfer into Level 3	0
Liabilities transfer out of Level 3	$ 0

Fair Value Measurements - Asset

Fair Value Measurements - Assets and liabilities measured at fair value on a recurring basis (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Fair Value
Assets, Carrying Amount	$ 5,788,826	$ 2,251,282
Liabilities, Carrying amount	957,957	784,363
Recurring basis \| Level 1 \| Cash and cash equivalents
Fair Value
Assets, Fair Value	87,573
Recurring basis \| Level 1 \| U.S. Treasuries
Fair Value
Assets, Fair Value	170,477
Recurring basis \| Level 1 \| Equity securities
Fair Value
Assets, Fair Value	120,302
Recurring basis \| Level 2 \| Convertible senior notes
Fair Value
Liabilities, Fair value	1,320,194	1,272,766
Recurring basis \| Level 2 \| Cash and cash equivalents
Fair Value
Assets, Fair Value	53,740
Recurring basis \| Level 2 \| Corporate bonds
Fair Value
Assets, Fair Value	705,084
Recurring basis \| Level 2 \| Commercial paper
Fair Value
Assets, Fair Value	329,722
Recurring basis \| Level 2 \| Municipal debt
Fair Value
Assets, Fair Value	9,984
Recurring basis \| Level 2 \| Certificates of deposit
Fair Value
Assets, Fair Value	27,454
Recurring basis \| Level 3 \| Contingent consideration
Fair Value
Liabilities, Fair value	9,990	9,760
Recurring basis \| Level 3 \| Long-term debt
Fair Value
Liabilities, Fair value	160,484	175,402
Recurring basis \| Level 3 \| Finance obligations
Fair Value
Liabilities, Fair value	195,805	181,553
Carrying value \| Recurring basis \| Contingent consideration
Fair Value
Liabilities, Carrying amount	9,990	9,760
Carrying value \| Recurring basis \| Convertible senior notes
Fair Value
Liabilities, Carrying amount	192,011	85,640
Carrying value \| Recurring basis \| Long-term debt
Fair Value
Liabilities, Carrying amount	160,484	175,402
Carrying value \| Recurring basis \| Finance obligations
Fair Value
Liabilities, Carrying amount	195,805	181,553
Carrying value \| Recurring basis \| Cash and cash equivalents
Fair Value
Assets, Carrying Amount	141,313
Carrying value \| Recurring basis \| Corporate bonds
Fair Value
Assets, Carrying Amount	705,084
Carrying value \| Recurring basis \| Commercial paper
Fair Value
Assets, Carrying Amount	329,722
Carrying value \| Recurring basis \| U.S. Treasuries
Fair Value
Assets, Carrying Amount	170,477
Carrying value \| Recurring basis \| Municipal debt
Fair Value
Assets, Carrying Amount	9,984
Carrying value \| Recurring basis \| Certificates of deposit
Fair Value
Assets, Carrying Amount	27,454
Carrying value \| Recurring basis \| Equity securities
Fair Value
Assets, Carrying Amount	120,302
Fair value \| Recurring basis \| Contingent consideration
Fair Value
Liabilities, Fair value	9,990	9,760
Fair value \| Recurring basis \| Convertible senior notes
Fair Value
Liabilities, Fair value	1,320,194	1,272,766
Fair value \| Recurring basis \| Long-term debt
Fair Value
Liabilities, Fair value	160,484	175,402
Fair value \| Recurring basis \| Finance obligations
Fair Value
Liabilities, Fair value	195,805	$ 181,553
Fair value \| Recurring basis \| Cash and cash equivalents
Fair Value
Assets, Fair Value	141,313
Fair value \| Recurring basis \| Corporate bonds
Fair Value
Assets, Fair Value	705,084
Fair value \| Recurring basis \| Commercial paper
Fair Value
Assets, Fair Value	329,722
Fair value \| Recurring basis \| U.S. Treasuries
Fair Value
Assets, Fair Value	170,477
Fair value \| Recurring basis \| Municipal debt
Fair Value
Assets, Fair Value	9,984
Fair value \| Recurring basis \| Certificates of deposit
Fair Value
Assets, Fair Value	27,454
Fair value \| Recurring basis \| Equity securities
Fair Value
Assets, Fair Value	$ 120,302

Operating and Finance Lease L_3

Operating and Finance Lease Liabilities - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Rental expense for all operating lease	$ 8,200	$ 7,800	$ 16,300	$ 12,500
Gross profit on sale leaseback transactions	19,500	14,400	35,400	19,700
Right of use assets obtained in exchange for new operating lease liabilities	24,000	2,900	35,900	8,100
Right of use assets, operating lease	172,300		172,300		$ 136,900
Amortization of right-of-use asset from operating lease	26,500		26,500		19,900
Right of use assets, finance lease	17,300		17,300		5,700
Amortization of right-of-use asset from finance lease	380		380		102
Prepaid rent and security deposit	3,100		3,100		$ 5,800
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 6,500	$ 700	$ 12,100	$ 700
Minimum
Lessee, Lease, Description [Line Items]
Lease Term - as Lessee	1 year		1 year
Maximum
Lessee, Lease, Description [Line Items]
Lease Term - as Lessee	9 years		9 years

Operating and Finance Lease L_4

Operating and Finance Lease Liabilities - Future minimum lease payments under operating and finance leases (Details) $ in Thousands	Jun. 30, 2021USD ($)
Future minimum lease payments under operating lease
Remainder of 2021	$ 17,298
2022	34,579
2023	34,636
2024	34,636
2025 and thereafter	73,276
Total future minimum lease payments	194,425
Less imputed lease interest	(52,307)
Total operating lease, liabilities	142,118
Future minimum lease payments under finance leases
Remainder of 2021	1,826
2022	3,731
2023	3,708
2024	3,715
2025 and thereafter	4,921
Total future minimum lease payments	17,901
Less imputed lease interest	(2,793)
Total finance lease liabilities	15,108
Future minimum lease payments under operating and finance leases
Remainder of 2021	19,124
2022	38,310
2023	38,344
2024	38,351
2025 and thereafter	78,197
Total future minimum payments	212,326
Less imputed interest	(55,100)
Total	$ 157,226

Operating and Finance Lease L_5

Operating and Finance Lease Liabilities - Other information related to the operating leases (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Lessee, Operating Lease, Description [Abstract]
Cash payments	$ 16,081	$ 9,674
Weighted average remaining lease term (in years)	5 years 9 months 25 days	4 years 4 months 2 days
Weighted average discount rate (as a percent)	11.40%	12.10%

Operating and Finance Lease L_6

Operating and Finance Lease Liabilities - Other information related to the finance leases (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Other information
Cash payments	$ 1,166	$ 132
Weighted average remaining lease term (years)	4 years 10 months 9 days	6 years 8 months 26 days
Weighted average discount rate	6.90%	9.60%

Finance Obligations - Narrative

Finance Obligations - Narrative (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Sale Leaseback Transaction [Line Items]
Total operating lease, liabilities	$ 142,118
Short term operating lease obligation	19,915	$ 14,314
Long term operating lease obligation	122,203	99,624
Total finance lease liabilities	15,108
Short term finance lease obligation	2,728	903
Long term finance lease obligation	12,380	4,493
Sale Leaseback Agreements
Sale Leaseback Transaction [Line Items]
Total finance lease liabilities	19,538	23,900
Short term finance lease obligation	6,500	8,000
Long term finance lease obligation	13,000	15,900
Sale Leaseback Agreements \| Future Services [Member]
Sale Leaseback Transaction [Line Items]
Total finance lease liabilities	176,300	157,700
Short term finance lease obligation	27,300	24,200
Long term finance lease obligation	$ 149,000	$ 133,500

Finance Obligations - Future mi

Finance Obligations - Future minimum payments under finance obligations (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Future minimum lease payments under finance leases
Remainder of 2021	$ 1,826
2022	3,731
2023	3,708
2024	3,715
2025 and thereafter	4,921
Total future minimum lease payments	17,901
Less imputed lease interest	(2,793)
Total finance lease liabilities	15,108
Finance obligation
Future minimum lease payments under finance leases
Remainder of 2021	27,737
2022	51,140
2023	49,313
2024	62,319
2025 and thereafter	72,708
Total future minimum lease payments	263,217
Less imputed lease interest	(67,412)
Total finance lease liabilities	195,805
Sale of Future Revenue - Debt
Future minimum lease payments under finance leases
Remainder of 2021	23,525
2022	46,165
2023	46,165
2024	46,165
2025 and thereafter	72,708
Total future minimum lease payments	234,728
Less imputed lease interest	(58,461)
Total finance lease liabilities	176,267
Sale Leaseback Agreements
Future minimum lease payments under finance leases
Remainder of 2021	4,212
2022	4,975
2023	3,148
2024	16,154
Total future minimum lease payments	28,489
Less imputed lease interest	(8,951)
Total finance lease liabilities	$ 19,538	$ 23,900

Finance Obligations - Other inf

Finance Obligations - Other information related to finance obligations (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Sale Leaseback Transaction [Line Items]
Cash payments	$ 1,166,000	$ 132,000
Weighted average remaining term (years)	4 years 10 months 9 days	6 years 8 months 26 days
Weighted average discount rate	6.90%	9.60%
Finance obligation
Sale Leaseback Transaction [Line Items]
Cash payments	$ 26,508	$ 20,148
Weighted average remaining term (years)	4 years 10 months 24 days	4 years 3 months 18 days
Weighted average discount rate	11.30%	11.20%

Investments - Available-for-sal

Investments - Available-for-sale securities (Details) $ in Thousands	Jun. 30, 2021USD ($)
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 1,244,618
Gross Unrealized Gains	304
Gross Unrealized Losses	(2,201)
Fair Value	1,242,721
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	707,022
Gross Unrealized Gains	51
Gross Unrealized Losses	(1,989)
Fair Value	705,084
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	329,471
Gross Unrealized Gains	253
Gross Unrealized Losses	(2)
Fair Value	329,722
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	27,460
Gross Unrealized Losses	(6)
Fair Value	27,454
U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	170,672
Gross Unrealized Losses	(195)
Fair Value	170,477
Municipal debt
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	9,993
Gross Unrealized Losses	(9)
Fair Value	$ 9,984

Investments - Equity Securities

Investments - Equity Securities (Details) $ in Thousands	6 Months Ended
Investments - Equity Securities (Details) $ in Thousands	Jun. 30, 2021USD ($)
Debt and Equity Securities, FV-NI [Line Items]
Cost	$ 119,978
Gross Unrealized Gains	405
Gross Unrealized Losses	(81)
Fair Value	120,302
Fixed income mutual funds
Debt and Equity Securities, FV-NI [Line Items]
Cost	89,962
Gross Unrealized Gains	17
Gross Unrealized Losses	(81)
Fair Value	89,898
Exchange traded mutual funds
Debt and Equity Securities, FV-NI [Line Items]
Cost	30,016
Gross Unrealized Gains	388
Fair Value	$ 30,404

Investments - Contractual Matur

Investments - Contractual Maturity (Details) $ in Thousands	Jun. 30, 2021USD ($)
Amortized Cost
Within one year	$ 717,531
After one through five years	527,087
Amortized Cost	1,244,618
Fair Value
Within one year	717,285
After one through five years	525,436
Total available-for-sale securities	$ 1,242,721

Commitments and Contingencies -

Commitments and Contingencies - Concentrations of Credit Risk (Details) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021USD ($)customer	Jun. 30, 2020customer	Jun. 30, 2021USD ($)customer	Jun. 30, 2020customer	Dec. 31, 2020customer
Customer Concentration
Restricted cash \| $	$ 243.5		$ 243.5
Letter of Credit
Customer Concentration
Restricted Cash \| $	$ 143.7		$ 143.7
Accounts receivable \| Customer concentration \| One customers
Customer Concentration
Number of customers	1		1
Concentration risk (as a percent)			78.50%
Accounts receivable \| Customer concentration \| Three customers
Customer Concentration
Number of customers					3
Concentration risk (as a percent)					73.90%
Revenues \| Customer concentration \| Two customers
Customer Concentration
Number of customers		2		2
Concentration risk (as a percent)		83.90%		77.90%
Revenues \| Customer concentration \| Three customers
Customer Concentration
Number of customers	3		3
Concentration risk (as a percent)	81.30%		77.70%

Employee Benefit Plans - Assump

Employee Benefit Plans - Assumptions For Estimating Fair Value (Details) - USD ($) $ in Millions	May 12, 2011	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Jul. 31, 2021	Dec. 31, 2020
Employee Benefit Plans
Stock options granted				698,500	174,649
Stock options
Employee Benefit Plans
Number of options outstanding (in shares)		9,165,066		9,165,066			10,284,498
Compensation cost		$ 4.3	$ 1.5	$ 7.6	$ 2.9
Stock options granted				698,500
Assumptions for estimating fair value
Dividend Yield				0.00%
Expected term of options (years)				5 years	6 years
Risk Free interest rate, minimum (as a percent)				0.61%	0.45%
Risk Free interest rate, maximum (as a percent)				1.04%	1.37%
Volatility, minimum (as a percent)				72.46%	64.19%
Volatility, maximum (as a percent)				73.69%	64.80%
the 2011 Plan
Employee Benefit Plans
Compensation cost		$ 11.1	$ 2.5	$ 19.6	$ 5
the 2011 Plan \| Stock options
Employee Benefit Plans
Maximum number of common stock shares available for issuance	1,000,000	42,400,000		42,400,000
Aggregate number of options granted (in shares)		9,200,000		9,200,000
Expiration period				10 years
Stock options granted	0
the 2011 Plan \| Stock options \| Minimum
Employee Benefit Plans
Vesting period				1 year
the 2011 Plan \| Stock options \| Maximum
Employee Benefit Plans
Vesting period				3 years
the 2011 Plan \| Employees \| Stock options
Employee Benefit Plans
Vesting period				3 years
Expiration period				10 years
the 2011 Plan \| Board of Directors \| Stock options
Employee Benefit Plans
Vesting period				1 year
2021 Stock Option Incentive Plan
Employee Benefit Plans
Maximum number of common stock shares available for issuance						22,500,000

Employee Benefit Plans - Stock

Employee Benefit Plans - Stock Activity, Weighted Average Exercise Price (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Shares
Granted (in shares)			698,500	174,649
Stock options
Shares
Options outstanding, beginning balance (in shares)			10,284,498
Granted (in shares)			698,500
Exercised (in shares)			(1,812,099)
Forfeited (in shares)			(5,833)
Options outstanding, end balance (in shares)	9,165,066		9,165,066		10,284,498
Options exercisable (in shares)	2,523,341		2,523,341
Options unvested (in shares)	6,641,725		6,641,725
Weighted Average Exercise Price
Options outstanding, beginning balance, weighted-average exercise price			$ 5.78
Granted, weighted-average exercise price			46.82
Exercised, weighted-average exercise price			2.65
Forfeited, weighted-average exercise price			6.78
Options outstanding, end balance, weighted-average exercise price	$ 9.51		9.51		$ 5.78
Options exercisable, weighted-average exercise price	2.17		2.17
Options unvested, weighted-average exercise price	$ 12.30		$ 12.30
Stock option activity additional disclosures
Options outstanding, weighted-average remaining contractual term			7 years 10 months 24 days		7 years 9 months 18 days
Options exercisable, weighted-average remaining contractual term			5 years 7 months 6 days
Options unvested, weighted-average remaining contractual term			8 years 8 months 12 days
Options outstanding, aggregate intrinsic value	$ 226,164		$ 226,164		$ 289,316
Options exercisable, aggregate intrinsic value	80,808		80,808
Options unvested, aggregate intrinsic value	$ 145,356		$ 145,356
Weighted-average grant date fair value of options granted (per share)	$ 29.23	$ 4.88	$ 46.67	$ 7.73
Unrecognized compensation cost	$ 38,300		$ 38,300
Period for recognition			3 years
Fair value of stock options that vested during the period	$ 432,000	$ 493,000	$ 520,000	$ 516,000

Employee Benefit Plans - Restri

Employee Benefit Plans - Restricted Stock Activity (Details) - Restricted stock outstanding - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Employee Benefit Plans
Compensation cost	$ 6,800	$ 932,000	$ 12,000	$ 2,000
Unrecognized compensation cost	$ 67,000	$ 6,900	$ 67,000	$ 6,900
Period for recognition			3 years
Shares
Unvested restricted stock, beginning balance (in shares)			5,874,642
Granted (in shares)			653,000
Vested (in shares)			(149,650)
Forfeited (in shares)			(5,833)
Unvested restricted stock, end balance (in shares)	6,372,159		6,372,159
Aggregate Intrinsic Value
Unvested restricted stock aggregate intrinsic value	$ 217,864		$ 217,864
Minimum
Employee Benefit Plans
Vesting period			1 year
Maximum
Employee Benefit Plans
Vesting period			3 years

Employee Benefit Plans - 401(K)

Employee Benefit Plans - 401(K) Saving And Retirement Plan (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Non Employee Director
Employee Benefit Plan Compensation
Granted (in shares)	2,585	7,657	5,238	22,490
Compensation cost	$ 94	$ 55	$ 179	$ 111
Savings And Retirement Plan 401 K
401(K) Savings & Retirement Plan
Percent of salary employee is permitted to contribute			100.00%
Vesting period			3 years
Common stock, shares issued			12,513	175,978
Total expense (including issuance of shares)	$ 900	$ 800	$ 2,200	$ 1,300