Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities
Net loss	$ (41,964)	$ (49,129)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation	1,499	1,591
Amortization and accretion	7,408	6,585
Stock-based compensation	8,749	10,529
Other non-cash	1,116	(39)
Changes in operating assets and liabilities
Accounts receivable, net	9,872	(4,587)
Inventory	(1,052)	1,048
Prepaid, current and other assets	(4,286)	(2,410)
Accounts payable, accrued expenses and other current liabilities	(10,297)	(3,952)
Operating lease liabilities	(1,846)	(1,458)
Deferred revenue	747	0
Net cash used in operating activities	(30,054)	(41,822)
Cash flows from investing activities
Purchase of available-for-sale investments	(25,236)	(15,834)
Proceeds from sales and maturities of investments	28,288	50,557
Purchase of property, plant and equipment	(772)	(1,240)
Net cash provided by investing activities	2,280	33,483
Cash flows from financing activities
Payments related to issuance of stock for stock-based compensation arrangements, net	(1,101)	(1,422)
Net cash used in financing activities	(1,101)	(1,422)
Net change in cash and cash equivalents	(28,875)	(9,761)
Cash and cash equivalents, at beginning of period	151,570	143,940
Cash and cash equivalents, at end of period	122,695	134,179
Non-cash investing and financing activities
Purchase of property, plant and equipment	$ 182	$ 254