Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (59,656)	$ (47,530)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,561	1,574
Stock-based compensation	10,052	2,766
Accretion on asset retirement obligation	26	29
Change in fair value of warrant liabilities	(116)	6,739
Loss on disposal of property and equipment	1	9
Inventory lower of cost or market adjustment	0	647
Amortization of debt discount and interest accrual	2,703	2,453
Changes in operating assets and liabilities:
Accounts receivable	(2,351)	3,158
Inventory	(22,412)	(11,143)
Deposits on purchased inventory	1,478	(3,593)
Deferred cost of revenue	2,327	(6,481)
Prepaid expenses and other assets	(2,262)	(2,124)
Accounts payable	(4,067)	2,108
Accrued expenses and other long-term liabilities	6,732	2,519
Customer deposits and deferred revenue	(12,445)	5,175
Net cash used in operating activities	(77,429)	(43,694)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	(2,814)	(1,117)
Net cash used in investing activities	(2,814)	(1,117)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from the exercise of stock options	3,571	247
Net cash provided by financing activities	224,635	65,026
NET INCREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	144,392	20,215
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — BEGINNING OF PERIOD	58,532	15,341
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — END OF PERIOD	202,924	35,556
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for interest	3,055	2,919
Cash paid for taxes	0	25
SUPPLEMENTAL NON-CASH INVESTING AND FINANCING ACTIVITIES:
Transfer of inventory and deferred cost of revenue to property and equipment	1,700	125
Purchase of property and equipment in accounts payable and accrued liabilities	129	277
Fair value of common stock warrants reclassified from liability to additional paid-in capital upon exercise	342	0
Public Offering
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from offering of common stock, gross	172,500	0
Payment of offering costs related to common stock issuance	(10,631)	0
Private Placement
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment of offering costs related to common stock issuance	0	(300)
Proceeds from offering of common stock, gross	0	26,100
At The Market Offering Program
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from offering of common stock, gross	278	40,126
Payment of offering costs related to common stock issuance	(6)	(1,147)
Direct Registered Offering
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from offering of common stock, gross	59,100	0
Payment of offering costs related to common stock issuance	$ (177)	$ 0