Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income (loss)	$ (228,421)	$ 875,668
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	(17,321)	(15,965)
Non-cash interest expense on liability related to sale of future royalties	12,040	9,994
Stock-based compensation	49,907	40,608
Depreciation and amortization	6,132	5,115
Accretion of discounts, net and other non-cash transactions	(7,826)	(3,991)
Changes in operating assets and liabilities:
Accounts receivable	5,914	(19,557)
Inventory	(1,807)	(1,158)
Other assets	15,818	(14,282)
Accounts payable	3,480	5,791
Accrued compensation	9,773	10,717
Other accrued expenses	15,508	15,417
Deferred revenue	(6,715)	(6,249)
Other liabilities	8,701	5,068
Net cash provided by (used in) operating activities	(134,817)	907,176
Cash flows from investing activities:
Purchases of investments	(603,702)	(989,850)
Maturities of investments	634,145	132,779
Sales of investments	0	11,963
Purchases of property, plant and equipment	(17,291)	(3,730)
Sales of property, plant and equipment	0	2,633
Net cash provided by (used in) investing activities	13,152	(846,205)
Cash flows from financing activities:
Issuance of common stock	0	790,231
Proceeds from shares issued under equity compensation plans	12,200	55,208
Net cash provided by financing activities	12,200	845,439
Effect of exchange rates on cash and cash equivalents	(16)	(47)
Net increase (decrease) in cash and cash equivalents	(109,481)	906,363
Cash and cash equivalents at beginning of period	194,905	4,762
Cash and cash equivalents at end of period	85,424	911,125
Supplemental disclosure of cash flow information:
Cash paid for interest	$ 9,455	$ 9,795