Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities:
Net loss attributable to NextDecade Corporation	$ (12,043)	$ (16,200)
Adjustment to reconcile net loss to net cash used in operating activities
Depreciation	41	29
Share-based compensation expense	5,338	12,234
Loss on Common Stock Warrant liabilities	197
(Gain) loss on investment securities	(184)	22
Realized gain on investment securities	(11)
Changes in operating assets and liabilities:
Prepaid expenses	(471)	(183)
Accounts payable	274	(156)
Accrued expenses and other liabilities	(1,148)	(1,543)
Net cash used in operating activities	(8,007)	(5,797)
Investing activities:
Acquisition of property, plant and equipment	(5,883)	(5,177)
Proceeds from sale of investment securities	17,000
Purchase of investment securities	(439)	(24)
Net cash provided by (used in) investing activities	10,678	(5,201)
Financing activities:
Preferred stock dividends	(11)
Shares repurchased related to share-based compensation	(260)
Net cash used in financing activities	(271)
Net increase (decrease) in cash and cash equivalents	2,400	(10,998)
Cash and cash equivalents – beginning of period	3,169	35,703
Cash and cash equivalents – end of period	5,569	24,705
Non-cash investing activities:
Accounts payable for acquisition of property, plant and equipment	864	175
Accrued liabilities for acquisition of property, plant and equipment	1,091	$ 4,471
Non-cash financing activities:
Paid-in-kind dividends on Series A and Series B Convertible Preferred Stock	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	$ 551