Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (22,645)	$ (116,445)	$ (67,865)
Adjustments to reconcile loss to net cash used in operating activities:
Depreciation and amortization	180	23	62
Stock-based compensation	30,917	18,806	13,960
Amortization of debt discount and debt issuance costs	1,644	2,183	2,332
Amortization of intangible asset	679	646	646
Deferred income taxes			11,082
Changes in assets and liabilities:
Accounts receivable, net	(49,907)	(21,205)	(25,333)
Inventory	(18,967)	(27,542)	(9,753)
Prepaid and other current assets	(10,366)	510	6,028
Other long-term assets	(900)		567
Accrued interest payable	(210)	(310)	(6,491)
Deferred revenue	136	1,656	1,221
Accounts payable and other current liabilities	65,913	37,602	40,267
Other long-term liabilities	(5,840)	9,373	440
Net cash used in operating activities	(9,366)	(94,703)	(32,837)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of furniture, fixtures and equipment	(2,478)	(58)	(12)
Net cash used in investing activities	(2,478)	(58)	(12)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of exchangeable debt			30,000
Proceeds from issuance of common stock, net of transaction costs	440,108	264,840
Proceeds from issuance of common stock under employee stock purchase plan	2,165	1,043
Proceeds from exercise of stock options, net of transaction costs	24,478	26,402	638
Payment of debt issuance costs			(1,207)
Payment of transaction costs for conversion of preferred stock		(39)
Repurchase of exchangeable senior notes, including transaction costs			(15,107)
Payment on long-term debt from royalty-bearing instrument	(31,652)	(14,690)	(3,322)
Transaction costs related to exchange of exchangeable senior notes		(121)
Taxes related to stock-based awards	(25,487)	(6,184)	(2,767)
Net cash provided by financing activities	409,612	271,251	8,235
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH	397,768	176,490	(24,614)
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF PERIOD	250,727	74,237	98,851
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH, END OF PERIOD	648,495	250,727	74,237
Cash paid during the year for:
Interest	4,591	21,527	17,241
Income taxes	67	850	$ 1,753
Supplemental disclosure of non-cash transactions:
Laxdale milestone	8,457
Initial recognition of operating lease right-of-use asset	$ 8,995
Exchange of exchangeable senior notes into common stock		29,490
Conversion of Series A Convertible Preferred Stock into common stock		$ 2,514