Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net loss	$ (183,101)	$ (199,581)	$ (232,569)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation	6,366	5,138	2,442
Amortization and accretion	27,792	12,976	1,646
Acquisition of assets expensed to research and development	0	10,171	0
Stock-based compensation	40,095	45,093	38,728
Induced conversion of 2014 Convertible Notes	0	0	24,059
Other non-cash	(732)	(271)	(270)
Changes in operating assets and liabilities
Accounts receivable, net	(17,668)	(35,639)	(2,715)
Inventory	(5,166)	(10,257)	(9,689)
Prepaid, current and other assets	340	(2,144)	(791)
Accounts payable, accrued expenses and other current liabilities	22,536	28,766	26,583
Operating lease liabilities	(6,010)	(4,682)	0
Deferred revenue	50,858	0	0
Net cash used in operating activities	(64,690)	(150,430)	(152,576)
Cash flows from investing activities
Acquisition of assets	0	(7,835)	0
Purchase of available-for-sale investments	(116,591)	(165,454)	(56,195)
Proceeds from sales and maturities of investments	192,870	0	108,297
Purchase of property, plant and equipment	(3,100)	(9,958)	(31,313)
Net cash provided (used in) by investing activities	73,179	(183,247)	20,789
Cash flows from financing activities
Proceeds from loan	8,274	0	0
Repayment of loan	(8,274)	0	0
Proceeds from sale of common stock, net	0	0	135,972
Proceeds related to issuance of stock for stock-based compensation arrangements, net	(859)	684	3,630
Proceeds from exercise of warrants	0	761	0
Proceeds from convertible notes, net of issuance costs	0	308,349	0
Payments of issuance costs	0	(1,769)	(1,883)
Payment for capped call options	0	(32,890)	0
Other financing	0	(336)	(683)
Net cash (used in) provided by financing activities	(859)	274,799	137,036
Net change in cash and cash equivalents	7,630	(58,878)	5,249
Cash and cash equivalents, at beginning of period	143,940	202,818	197,569
Cash and cash equivalents, at end of period	151,570	143,940	202,818
Supplemental disclosures
Cash paid for interest	5,034	6,496	1,774
Cash paid for income taxes	4,987	0	0
Non-cash investing and financing activities:
Conversion of convertible notes to common stock (Note 10)	0	0	148,078
Liabilities incurred from Avizorex Asset Acquisition	0	1,186	0
Purchases of property, plant and equipment in accounts payable and accrued expense and other current liabilities	374	771	3,526
Build-to-suit lease transaction (Note 7)