Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities:
Net loss	$ (59,217)	$ (44,315)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	4,971	2,804
Depreciation and amortization	50	366
Amortization of debt issuance costs and debt discount	0	506
Inventory write-down	0	2,232
Asset impairment charges	0	920
Change in fair value of common stock warrant liabilities	31	(740)
Change in fair value of contingent consideration	(2,500)	1,100
Changes in operating assets and liabilities:
Trade accounts receivable	0	7,893
Inventory	0	2,583
Prepaid expenses and other current assets	(3,482)	2,602
Other assets	2,891	(848)
Accounts payable, accrued and other liabilities	1,689	150
Deferred revenue	0	(1,245)
Net cash used in operating activities	(55,567)	(25,992)
Investing activities:
Purchases of property and equipment	(84)	(35)
Net cash used in investing activities	(84)	(35)
Financing activities:
Proceeds from issuance of common stock under equity incentive plans	5,427	237
Taxes paid related to net share settlement of equity awards	(1,426)	0
Proceeds from issuance of common stock under an at-the-market offering, net of issuance costs	30,250	0
Net cash provided by financing activities	34,251	237
Net decrease in cash and cash equivalents	(21,400)	(25,790)
Cash and cash equivalents, beginning of the period	293,503	91,551
Cash and cash equivalents, end of the period	$ 272,103	$ 65,761