Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net loss	$ (24,644)	$ (9,736)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	10,577	8,529
Depreciation	3,925	3,622
Amortization of intangible assets	977	968
Amortization of deferred financing costs	282	109
Loss on disposal of property and equipment	97	332
Amortization (accretion) of investments	127	(735)
Change in value of contingent consideration	(5,046)	(3,872)
Other non-cash adjustments to income	656	404
Changes in operating assets and liabilities:
Accounts receivable	5,127	(2,859)
Inventories	(3,402)	(1,966)
Other current assets	(7)	(710)
Accounts payable	(1,970)	2,407
Accrued liabilities	(14,841)	(5,845)
Other noncurrent assets and liabilities	507	(340)
Net cash used in operating activities	(27,635)	(9,692)
Cash flows from investing activities:
Purchases of available-for-sale securities	(127,069)	(31,627)
Sales and maturities of available-for-sale securities	33,732	46,162
Purchases of property and equipment	(2,944)	(4,456)
Proceeds from sale of property and equipment		8
Proceeds from capital grant	800
Net cash (used in) provided by investing activities	(95,481)	10,087
Cash flows from financing activities:
Proceeds from sale of stock, net of offering costs of $218 and $0, respectively	188,958
Payments of debt and leases	(280)	(303)
Payments of debt fees	(4)	(300)
Proceeds from stock option exercises and employee stock purchase plan	6,889	2,024
Shares repurchased for payment of taxes on stock awards	(12,323)	(8,695)
Net cash provided by (used in) financing activities	183,240	(7,274)
Effect of exchange rate changes on cash and cash equivalents	(85)	(105)
Net increase (decrease) in cash and cash equivalents	60,039	(6,984)
Cash and cash equivalents-beginning of period	28,483	32,231
Cash and cash equivalents-end of period	88,522	25,247
Supplemental cash flow information:
Cash paid for interest	2,195	1,746
Cash paid for income taxes	282	185
Non-cash investing and financing activities:
Accrued purchases of property and equipment	$ 525	$ 877