Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities
Net loss	$ (130,164)	$ (140,245)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	41,855	40,305
Amortization of premiums and accretion of discounts on investment securities	481	(1,995)
Amortization of intangible assets	739	739
Loss on strategic investment	1,060	241
Depreciation	648	741
Changes in operating assets and liabilities:
Accounts receivable, net	(8,004)	(5,691)
Interest and other receivables	(250)	758
Inventory	(20)	273
Prepaid expenses	(6,240)	2,220
Operating lease right-of-use assets	2,025	1,133
Other assets	66	70
Accounts payable	(756)	1,483
Accrued liabilities	11,853	(1,576)
Operating lease liabilities	(862)	(1,077)
Long-term liabilities	1,684	49
Net cash used in operating activities	(85,885)	(102,572)
Cash flows from investing activities
Purchases of investment securities	(100,813)	(176,677)
Maturities of investment securities	261,153	210,904
Purchases of property and equipment	(3,867)	(842)
Net cash provided by investing activities	156,473	33,385
Cash flows from financing activities
Proceeds from issuance of common stock, net of issuance costs	51,155	8,822
Net cash provided by financing activities	51,155	8,822
Effect of exchange rate changes on cash	1
Net increase (decrease) in cash, cash equivalents and restricted cash	121,744	(60,365)
Cash, cash equivalents and restricted cash
Beginning of period	194,467	139,584
End of period	316,211	79,219
Supplemental disclosure of noncash information:
Property and equipment purchases in accounts payable and accrued liabilities	$ 288	$ 17