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 income (loss)	$ 37,012	$ 21,111	$ (142,542)
Reconciliation of net income (loss) to net cash provided by (used in) operating activities:
Share-based compensation expense	75,262	58,068	42,522
Depreciation	7,452	4,024	2,400
Amortization of debt discount	18,922	17,552	10,937
Amortization of debt issuance costs	1,389	1,326	848
Net (accretion of discounts) amortization of premiums on investments	(1,965)	1,449	1,756
Change in fair value of restricted equity securities	12,987	0	0
Other, net	754	(409)	(1,445)
Changes in operating assets and liabilities:
Accounts receivable	(69,169)	(25,113)	(31,127)
Inventory	(6,424)	(3,524)	(1,024)
Accounts payable and accrued liabilities	53,955	24,223	27,338
Other changes in operating assets and liabilities, net	21,879	2,657	(3,994)
Net cash provided by (used in) operating activities	152,054	101,364	(94,331)
Cash Flows from Investing Activities:
Purchases of marketable securities	(797,169)	(545,962)	(583,408)
Sales and maturities of marketable securities	669,691	327,825	339,088
Purchase of restricted equity securities	(68,855)	0	0
Purchases of property and equipment	(14,748)	(24,812)	(6,940)
Proceeds from sales of property and equipment	8	34	7
Net cash used in investing activities	(211,073)	(242,915)	(251,253)
Cash Flows from Financing Activities:
Issuance of common stock	27,313	29,530	13,865
Proceeds from issuance of convertible senior notes, net	0	0	502,781
Net cash provided by financing activities	27,313	29,530	516,646
Change in cash and cash equivalents and restricted cash	(31,706)	(112,021)	171,062
Cash and cash equivalents and restricted cash at beginning of period	147,191	259,212	88,150
Cash and cash equivalents and restricted cash at end of period	115,485	147,191	259,212
Supplemental Disclosure:
Cash paid for interest	11,644	11,644	6,242
Cash paid for income taxes	507	0	0
Non-cash capital expenditures	$ 953	$ 2,318	$ 0