Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income	$ 636,667	$ 185,803
Adjustments to reconcile net income to net cash provided by operating activities:
Gain from sale of Promacta license	(812,797)	0
Non-cash change in estimated fair value of contingent liabilities	762	3,637
Depreciation and amortization	12,560	11,421
Amortization of discount on investments, net	(7,477)	(3,780)
Amortization of debt discount and issuance fees	22,562	25,155
Amortization of other economic rights	9,135	0
Share-based compensation	18,215	14,837
Deferred income taxes	57,766	44,149
Loss (gain) from investment in Viking	5,592	(121,679)
Other	(1,249)	(976)
Royalties recorded in retained earnings upon adoption of ASC 606	0	32,707
Changes in operating assets and liabilities, net of effects from acquisition:
Accounts receivable, net	33,892	(21,380)
Inventory	(1,500)	(3,763)
Accounts payable and accrued liabilities	(3,374)	(42)
Income tax payable	16,571	0
Other economic rights	(12,000)	0
Other	2,678	(4,602)
Net cash provided by (used in) operating activities	(21,997)	161,487
Cash flows from investing activities:
Proceeds from sale of Promacta license	812,797	0
Purchase of short-term investments	(1,682,586)	(1,158,290)
Proceeds from sale of short-term investments	144,182	75,993
Proceeds from maturity of short-term investments	1,274,851	381,690
Cash paid for acquisition, net of cash acquired	(11,840)	0
Cash paid for equity method investment	(1,000)	0
Other	(6,307)	2,036
Net cash provided by (used in) investing activities	530,097	(698,571)
Cash flows from financing activities:
Repayment of debt	(27,323)	(21,785)
Gross proceeds from issuance of 2023 Notes	0	750,000
Payment of debt issuance costs	0	(16,900)
Proceeds from issuance of warrants	0	90,000
Purchase of convertible bond hedge	0	(140,250)
Proceeds from convertible bond hedge settlement	12,401	52,129
Payments to convert holders for bond conversion	(12,401)	0
Net proceeds from stock option exercises and ESPP	2,856	18,860
Taxes paid related to net share settlement of equity awards	(2,906)	(3,657)
Share repurchase	(371,106)	(52,727)
Payments to CVR Holders	(3,000)	0
Net cash provided by (used in) financing activities	(401,479)	675,670
Effect of exchange rate changes on cash	(88)	0
Net increase in cash, cash equivalents and restricted cash	106,533	138,586
Cash, cash equivalents and restricted cash at beginning of period	119,780	20,620
Cash, cash equivalents and restricted cash at end of period	226,313	159,206
Supplemental disclosure of cash flow information:
Interest paid	3,015	1,513
Taxes paid	93,817	341
Restricted cash in other current assets	1,011	0
Supplemental schedule of non-cash activity:
Accrued fixed asset purchases	0	4
Unrealized gain on AFS investments	699	0
Excess of conversion value over the principal amount of 2019 Notes paid in shares	0	(31,571)
Value of shares reacquired under convertible bond hedge transaction entered into with 2019 Notes	$ 0	$ 31,571