CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net income	$ 629,302	$ 143,321	$ 12,556
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Gain from sale of Promacta license	(812,797)	0	0
Change in estimated fair value of contingent liabilities	(30)	3,448	2,580
Realized gain on sale of short-term investment	(41)	(2,611)	(831)
Depreciation and amortization of intangible assets	18,361	12,784	10,955
(Gain) loss on equity investment in Viking	(2,888)	(47,658)	(1,114)
Amortization/accretion of premium (discount) on investments, net	(10,274)	(5,452)	(81)
Amortization of debt discount and issuance fees	29,988	43,954	11,619
Amortization of commercial license and other economic rights	25,370	1,934	759
Share-based compensation	24,515	20,846	24,915
Deferred income taxes, net	74,829	29,739	44,518
Royalties recorded in retained earnings upon adoption of ASC 606	0	32,707	0
Other	(1,456)	2,832	(870)
Changes in operating assets and liabilities, net of acquisition:
Accounts receivable, net	25,463	(29,544)	(8,358)
Inventory	(2,061)	(2,559)	(843)
Accounts payable and accrued liabilities	(6,826)	(4,542)	(1,713)
Income taxes receivable	(11,219)	318	(460)
Other economic rights	(12,000)	0	0
Other	2,428	(5,458)	(5,062)
Net cash provided by (used in) operating activities	(29,336)	194,059	88,570
Investing activities
Proceeds from sale of Promacta license	812,797	0	0
Purchase of commercial license rights	0	(10,000)	0
Cash paid for acquisition, net of cash acquired	(11,840)	(5,856)	(26,653)
Purchases of property and equipment	(2,553)	(887)	(2,156)
Purchases of short-term investments	(2,356,545)	(1,434,255)	(254,258)
Proceeds from sale of short-term investments	535,877	131,942	86,985
Proceeds from maturity of short-term investments	1,494,851	892,873	109,649
Proceeds from commercial license rights	0	0	7,054
Proceeds received from repayment of Viking note receivable	0	3,914	200
Cash paid for equity method investment	(1,000)	0	0
Other, net	(4,669)	(1,000)	0
Net cash provided by (used in) investing activities	466,918	(423,269)	(79,179)
Financing activities
Repayment of debt	(27,323)	(217,674)	0
Gross proceeds from issuance of 2023 Convertible Senior Notes	0	750,000	0
Payment of debt issuance costs	0	(16,900)	0
Proceeds from issuance of warrants	0	90,000	0
Purchase of convertible bond hedge	0	(140,250)	0
Proceeds from bond hedge settlement	12,401	439,559	0
Payments to convert holders for bond conversion	(12,401)	(439,581)	0
Net proceeds from stock option exercises and ESPP	2,997	20,183	4,517
Taxes paid related to net share settlement of equity awards	(4,418)	(3,765)	(10,074)
Share repurchases	(453,048)	(122,868)	(1,966)
Repurchase of warrants	(380)	(30,094)	0
Payments to CVR Holders	(3,000)	(25)	0
Net cash provided by (used in) financing activities	(485,172)	328,585	(7,523)
Net increase (decrease) in cash and cash equivalents	(47,590)	99,375	1,868
Effect of exchange rate changes on cash	83	(215)	0
Cash, cash equivalents and restricted cash at beginning of year	119,780	20,620	18,752
Cash, cash equivalents and restricted cash at end of year	72,273	119,780	20,620
Cash paid during the year:
Interest paid	5,827	1,513	1,838
Taxes paid	103,817	341	157
Restricted cash in other current assets	730	2,616	0
Supplemental schedule of non-cash investing and financing activities
Accrued inventory purchases	170	2,059	1,007
Unrealized gain on AFS investments	256	48	144
Purchase of fixed assets recorded in accounts payable	$ 495	$ 15	$ 0