Fair Value Measurements Level 3 Unobservable Input Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales			$ (108,169)
Change in fair value of acquired royalty rights, Level 3 Rollforward	$ 35,353	$ 16,085	132,224	$ (11,872)
Payments for (Proceeds from) Productive Assets			(74,404)	(47,240)
Change in fair value included in earnings for liabilities	(700)	$ (2,083)	(3,349)	$ (2,083)
Anniversary Payment [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	0		0		$ (88,001)
Change in fair value of acquired royalty rights			(999)
Contingent Consideration [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	(45,000)		(45,000)		$ (42,650)
Change in fair value of acquired royalty rights			(2,350)
Royalty right [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales			(108,169)
Beginning balance			402,318
Change in fair value of acquired royalty rights, Level 3 Rollforward			132,224
Ending balance	351,969		351,969
Payments for (Proceeds from) Productive Assets			(74,404)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			57,820
Depomed [Member] | Royalty right [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales			0
Beginning balance			164,070
Ending balance	222,695		222,695
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			58,625
VB [Member] | Royalty right [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales			0
Beginning balance			14,997
Ending balance	15,437		15,437
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			440
University of Michigan [Member] | Royalty right [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales			0
Beginning balance			35,386
Ending balance	35,449		35,449
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			63
ARIAD [Member] | Royalty right [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales			(108,169)
Beginning balance			108,631
Ending balance	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			(462)
AcelRx [Member] | Royalty right [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales			0
Beginning balance			67,483
Ending balance	74,065		74,065
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			6,582
Avinger [Member] | Royalty right [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales			0
Beginning balance			1,638
Ending balance	861		861
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			(777)
Kybella [Member] | Royalty right [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales			0
Beginning balance			10,113
Ending balance	$ 3,462		3,462
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			$ (6,651)