Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income (loss)	$ (327,229)	$ 779,525
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Non-cash royalty revenue related to sale of future royalties	(27,585)	(24,337)
Non-cash interest expense on liability related to sale of future royalties	17,853	14,808
Stock-based compensation	74,787	63,895
Depreciation and amortization	9,582	7,799
Accretion of discounts, net and other non-cash transactions	(10,421)	(8,136)
Changes in operating assets and liabilities:
Accounts receivable	2,008	(16,179)
Inventory	(2,339)	(2,570)
Other assets	18,127	(22,087)
Accounts payable	16,109	2,611
Accrued compensation	13,164	19,659
Other accrued expenses	10,019	26,603
Deferred revenue	(9,465)	(10,931)
Other liabilities	11,932	5,104
Net cash provided by (used in) operating activities	(203,458)	835,764
Cash flows from investing activities:
Purchases of investments	(1,028,883)	(1,944,178)
Maturities of investments	1,122,902	467,658
Sales of investments	0	11,963
Purchases of property, plant and equipment	(22,614)	(5,552)
Sales of property, plant and equipment	0	2,633
Net cash provided by (used in) investing activities	71,405	(1,467,476)
Cash flows from financing activities:
Issuance of common stock	0	790,231
Proceeds from shares issued under equity compensation plans	18,449	59,067
Net cash provided by financing activities	18,449	849,298
Effect of exchange rates on cash and cash equivalents	(77)	(87)
Net increase (decrease) in cash and cash equivalents	(113,681)	217,499
Cash and cash equivalents at beginning of period	194,905	4,762
Cash and cash equivalents at end of period	81,224	222,261
Supplemental disclosures of cash flow information:
Cash paid for interest	14,229	14,701
Operating lease right-of-use assets recognized in exchange for lease liabilities	$ 56,025	$ 0