Fair Value Measurements (Financial Instruments Measured at Fair Value on a Recurring Basis) (Detail) - USD ($) $ in Thousands	Jun. 30, 2015		Dec. 31, 2014
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Royalty rights	$ 280,731	[1]	$ 259,244	[2]
Financial assets:
Assets, Fair Value	427,448		487,415
Foreign Currency Contract, Asset, Fair Value Disclosure	6,985		4,069
Warrants and Rights Outstanding	1,258
Money Market Funds [Member]
Financial assets:
Cash and Cash Equivalents, Fair Value	136,454		221,792
Equity Securities [Member]
Financial assets:
Available for Sale Securities, Fair Value	2,020		2,310
Fair Value Level 1 [Member]
Financial assets:
Assets, Fair Value	136,454		221,792
Foreign Currency Contract, Asset, Fair Value Disclosure	0		0
Fair Value Level 1 [Member] | Money Market Funds [Member]
Financial assets:
Cash and Cash Equivalents, Fair Value	136,454		221,792
Fair Value Level 1 [Member] | Equity Securities [Member]
Financial assets:
Available for Sale Securities, Fair Value	0		0
Fair Value Level 2 [Member]
Financial assets:
Assets, Fair Value	10,263		6,379
Foreign Currency Contract, Asset, Fair Value Disclosure	6,985		4,069
Warrants and Rights Outstanding	1,258
Fair Value Level 2 [Member] | Money Market Funds [Member]
Financial assets:
Cash and Cash Equivalents, Fair Value	0		0
Fair Value Level 2 [Member] | Equity Securities [Member]
Financial assets:
Available for Sale Securities, Fair Value	2,020		2,310
Fair Value Level 3 [Member]
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Royalty rights	280,731		259,244
Financial assets:
Assets, Fair Value	$ 280,731		$ 259,244

[1] unaudited

[2] Note 1