Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating activities:
Net loss attributable to NextDecade Corporation	$ (22,039)	$ (14,329)
Adjustment to reconcile net loss to net cash used in operating activities
Depreciation	184	196
Share-based compensation expense (forfeiture)	(4,313)	(341)
Loss (gain) on Common Stock Warrant liabilities	2,533	(7,870)
Realized loss on investment securities	0	423
Amortization of right-of-use assets	551	1,230
Amortization of other non-current assets	1,416	1,360
Changes in operating assets and liabilities:
Prepaid expenses	(186)	191
Accounts payable	(26)	(370)
Operating lease liabilities	(548)	(874)
Accrued expenses and other liabilities	4,468	(5,869)
Net cash used in operating activities	(17,960)	(26,253)
Investing activities:
Acquisition of property, plant and equipment	(12,105)	(32,352)
Acquisition of other non-current assets	(6,429)	(10,911)
Proceeds from sale of investment securities	0	61,972
Purchase of investment securities	0	(188)
Net cash (used in) provided by investing activities	(18,534)	18,521
Financing activities:
Proceeds from sale of Rio Bravo Pipeline Company, LLC	0	15,000
Proceeds from sale of Series C Convertible Preferred Stock	39,500	0
Proceeds from sale of common stock	557	0
Equity issuance costs	(268)	0
Preferred stock dividends	(67)	(50)
Shares repurchased related to share-based compensation	(284)	(346)
Net cash provided by financing activities	39,438	14,604
Net increase in cash and cash equivalents	2,944	6,872
Cash and cash equivalents – beginning of period	22,608	15,736
Cash and cash equivalents – end of period	25,552	22,608
Non-cash investing activities:
Accounts payable for acquisition of property, plant and equipment	117	16
Accrued liabilities for acquisition of property, plant and equipment	926	650
Pipeline assets obtained in exchange for other non-current liabilities	84	7,916
Non-cash financing activities:
Paid-in-kind dividends on Convertible Preferred Stock	18,227	14,277
Accretion of deemed dividends on Series A Convertible Preferred Stock	63	128
Accrued liabilities for equity issuance costs	$ 35	$ 0