Fair Value Measurements (Narrative) (Detail) (USD $)	12 Months Ended			3 Months Ended	6 Months Ended	0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Dec. 30, 2014	Nov. 14, 2014	Nov. 06, 2014	Jun. 26, 2014	Oct. 18, 2013
Repayment of notes receivable	$ 68,800,000	$ 59,279,000	$ 5,000,000
Cash payment for purchase of royalty right							65,600,000
Royalty rights	259,244,000	235,677,000		259,244,000
Percentage of royalty acquired							75.00%
Transfers from level 1 to level 2, amount		0
Transfers from level 2 to level 1, amount	0	0		0
VB [Member]
Purchase of royalty right								15,500,000
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate, High End	17.50%			17.50%
Fair Value Measurements, Sensitivity Analysis, Description	Should this discount rate increase or decrease by 2.5%, the fair value of this asset could decrease by $1.4 million or increase by $1.6 million, respectively. Should the expected royalties increase or decrease by 2.5%, the fair value of the asset could increase by $0.4 million or decrease by $0.4 million, respectively.
Royalty rights	16,100,000			16,100,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	16,100,000			16,100,000
Glumetza [Member]
Proceeds from Royalties Received					51,700,000
Expected royalty payments					18,900,000
Asset at Fair Value, Changes in Fair Value Resulting from Changes in Assumptions				42,600,000
University of Michigan [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate, High End	12.80%			12.80%
Fair Value Measurements, Sensitivity Analysis, Description	Should this discount rate increase or decrease by 2.5%, the fair value of this asset could decrease by $6.4 million or increase by $7.4 million, respectively. Should the expected royalties increase or decrease by 5%, the fair value of the asset could increase by $3.3 million or decrease by $3.3 million, respectively.
Royalty rights	66,900,000			66,900,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	66,900,000			66,900,000
Direct Flow Medical Note Receivable [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate, High End	16.00%			16.00%
Kaleo [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate, High End	13.00%			13.00%
Depomed [Member]
Cash payment for purchase of royalty right									240,500,000
Purchase of royalty right									241,300,000
Royalty right purchase transaction costs									800,000
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate, Low End	21.00%			21.00%
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate, High End	25.00%			25.00%
Fair Value Measurements, Sensitivity Analysis, Description	Should these discount rates increase or decrease by 5%, the fair value of the asset could decrease by $19.8 million or increase by $25.2 million, respectively. A third-party expert was engaged to help management develop its original estimate of the expected future cash flows. The fair value of the asset is subject to variation should those cash flows vary significantly from those estimates. Should the expected cash flows from royalties increase or decrease by 10%, the fair value of the asset could increase by $14.2 million or decrease by $14.9 million, respectively.
Royalty rights	176,200,000			176,200,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	176,200,000			176,200,000
AxoGen [Member]
Repayment of notes receivable						$ 30,300,000