CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net loss	$ (87,404)	$ (35,558)
Adjustments to reconcile net loss to net cash used in operating activities:
Changes in fair value of warrant liabilities	0	(9,835)
Depreciation and amortization	804	313
Interest on non-recourse debt	9,962	10,626
Amortization of deferred revenue	0	13
Amortization of bond premiums	0	6
Amortization of debt issuance costs	13	(53)
Amortization of deferred rent	0	109
Right-of-use asset amortization	64	0
Decrease in allowance for doubtful accounts	0	(11)
Non-cash expense related to stock-based compensation	1,743	1,330
Changes in operating assets and liabilities	20,141	884
Net cash used in operating activities	(54,677)	(32,176)
Cash flows from investing activities
Purchases of marketable securities	0	(135)
Proceeds from sales/maturities of marketable securities	0	26,881
Purchases of property and equipment	(2,064)	(2,940)
Net cash (used in) provided by investing activities	(2,064)	23,806
Cash flows from financing activities:
Exercise of stock options, net	1,825	333
Exercise of warrants	0	5,250
Proceeds from private offering of common stock	0	67,784
Proceeds from the issuance of non-recourse debt	0	182,217
Debt conversion fees	0	(3)
Tax withholding payments for stock-based compensation	0	(1,472)
Net cash provided by financing activities	1,825	254,109
Effect of changes in exchange rates on cash, cash equivalents and restricted cash	(9)	47
Net increase (decrease) in cash, cash equivalents and restricted cash	(54,925)	245,786
Cash, cash equivalents and restricted cash beginning of period	494,173	60,960
Cash, cash equivalents and restricted cash end of period	439,248	306,746
Supplemental disclosure of cash flow information:
Interest paid	169	475
Schedule for non-cash investing and financing activities:
Non-cash component of warrant exercise	0	17,760
Accrued capital expenditures	3,140	1,439
Shares received in cashless exercise	1,271	0
Total cash, cash equivalents and restricted cash	$ 494,173	$ 60,960