Consolidated Statements Of Cash Flow - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net loss	$ (7,949)	$ (10,653)
Adjustments to reconcile net loss to net cash used for operating activities:
Depreciation and amortization	3,675	157
Amortization of debt issuance costs and discounts	(1,050)	5,414
Amortization of discount or premium on available-for-sale securities	(116)	121
Share-based compensation expense	468	925
Changes in assets and liabilities:
Accounts receivable	1,054	896
Inventories	1,186	(3,294)
Prepaid expenses and other assets	1,004	730
Accounts payable	(5,306)	(5,286)
Accrued and other liabilities	389	(707)
Deferred revenue	(295)	(291)
Net cash used for operating activities	(6,940)	(11,988)
Cash flows from investing activities:
Fixed asset purchases	(21)	(34)
Purchases of available-for-sale securities	(13,876)	(7,604)
Proceeds from maturity of available-for-sale securities	12,885	28,336
Proceeds from sales of available-for-sale securities	562	6,293
Net cash (used for) provided by investing activities	(450)	26,991
Cash flows from financing activities:
Repayments of notes payable		(4,590)
Net cash used for financing activities		(4,590)
Net (decrease) increase in cash and cash equivalents	(7,390)	10,413
Cash and cash equivalents:
Beginning of period	30,411	66,392
End of period	$ 23,021	$ 76,805