Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (20,553)	$ (24,431)
Adjustments to reconcile loss to net cash used in operating activities:
Depreciation and amortization	146	6
Accretion of investments	(151)
Stock-based compensation	10,591	6,883
Amortization of debt discount and debt issuance costs	289	446
Amortization of intangible asset	360	161
Changes in assets and liabilities:
Accounts receivable, net	(41,858)	(12,962)
Inventory	(15,352)	(107)
Prepaid and other current assets	(7,416)	(2,389)
Other long-term assets		(469)
Interest receivable	(1,021)
Accrued interest payable	(111)	(73)
Deferred revenue	961	(547)
Accounts payable and other current liabilities	79,285	(2,238)
Other long-term liabilities	(1,033)	(2,369)
Net cash provided by (used in) operating activities	4,137	(38,089)
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sales of securities	17,077
Purchase of securities	(310,648)
Purchases of furniture, fixtures and equipment	(251)
Net cash used in investing activities	(293,822)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options, net of transaction costs	1,306	15,456
Payment on debt from royalty-bearing instrument	(13,330)	(6,423)
Taxes paid related to stock-based awards	(13,831)	(9,080)
Net cash used in financing activities	(25,855)	(47)
NET DECREASE IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH	(315,540)	(38,136)
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF PERIOD	648,495	250,727
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH, END OF PERIOD	332,955	212,591
Cash paid during the year for:
Interest	$ 875	7,709
Supplemental disclosure of non-cash transactions:
Initial recognition of operating lease right-of-use asset		$ 8,995