Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating activities:
Net income (loss) attributable to NextDecade Corporation	$ 902	$ (12,043)
Adjustment to reconcile net income (loss) to net cash used in operating activities
Depreciation	16	41
Share-based compensation expense (forfeiture)	(1,860)	5,338
Gain (loss) on Common Stock Warrant liabilities	(8,339)	197
Gain on investment securities		(184)
Realized loss (gain) on investment securities	423	(11)
Amortization of right-of-use assets	324	184
Amortization of other non-current assets	177
Changes in operating assets and liabilities:
Prepaid expenses	(218)	(471)
Accounts payable	(28)	295
Operating lease liabilities	(271)	(205)
Accrued expenses and other liabilities	(5,364)	(1,148)
Net cash used in operating activities	(14,238)	(8,007)
Investing activities:
Acquisition of property, plant and equipment	(13,826)	(5,883)
Acquisition of other non-current assets	(6,107)
Proceeds from sale of investment securities	61,972	17,000
Purchase of investment securities	(188)	(439)
Net cash provided by investing activities	41,851	10,678
Financing activities:
Proceeds from sale of Rio Bravo	15,000
Preferred stock dividends	(13)	(11)
Shares repurchased related to share-based compensation	(57)	(260)
Net cash provided by (used in) financing activities	14,930	(271)
Net increase in cash and cash equivalents	42,543	2,400
Cash and cash equivalents – beginning of period	15,736	3,169
Cash and cash equivalents – end of period	58,279	5,569
Non-cash investing activities:
Accounts payable for acquisition of property, plant and equipment	3,341	864
Accrued liabilities for acquisition of property, plant and equipment	7,862	1,091
Non-cash financing activities:
Paid-in-kind dividends on Series A and Series B Convertible Preferred Stock	3,430	2,491
Dividends payable on Series A and Series B Convertible Preferred Stock charged to additional paid-in capital		2,481
Accretion of deemed dividends on Series A Convertible Preferred Stock	$ 76	$ 551