Fair Value Measurements (Financial Instruments Measured at Fair Value on a Recurring Basis) (Detail) - USD ($) $ in Thousands		Sep. 30, 2017		Jul. 03, 2017	Dec. 31, 2016		Jul. 01, 2016
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Royalty rights		$ 351,969	[1]		$ 402,318	[2]
Financial assets:
Assets, Fair Value		373,132			497,387
Warrants and Rights Outstanding		49			78
Financial liabilites:
Anniversary payment		0	[1]	$ 89,000	88,001	[1]	$ 87,000
Business Combination, Contingent Consideration, Liability, Noncurrent	[1]	45,000			42,650
Liabilities, Fair Value Disclosure, Recurring		45,000			130,651
Money Market Funds [Member]
Financial assets:
Cash and Cash Equivalents, Fair Value		14,705			4
Certificates of Deposit [Member]
Financial assets:
Available for Sale Securities, Fair Value		0			75,000
Commercial Paper [Member]
Financial assets:
Available for Sale Securities, Fair Value		2,060			19,987
Equity Securities [Member]
Financial assets:
Available for Sale Securities, Fair Value		4,349			0
Fair Value Level 1 [Member]
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and Nonfinancial Liabilities, Fair Value Disclosure		0			0
Financial assets:
Assets, Fair Value		19,054			4
Fair Value Level 1 [Member] | Money Market Funds [Member]
Financial assets:
Cash and Cash Equivalents, Fair Value		14,705			4
Fair Value Level 1 [Member] | Certificates of Deposit [Member]
Financial assets:
Available for Sale Securities, Fair Value		0			0
Fair Value Level 1 [Member] | Commercial Paper [Member]
Financial assets:
Available for Sale Securities, Fair Value		0			0
Fair Value Level 1 [Member] | Equity Securities [Member]
Financial assets:
Available for Sale Securities, Fair Value		4,349			0
Fair Value Level 2 [Member]
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and Nonfinancial Liabilities, Fair Value Disclosure		0			0
Financial assets:
Assets, Fair Value		2,109			95,065
Warrants and Rights Outstanding		49			78
Fair Value Level 2 [Member] | Money Market Funds [Member]
Financial assets:
Cash and Cash Equivalents, Fair Value		0			0
Fair Value Level 2 [Member] | Certificates of Deposit [Member]
Financial assets:
Available for Sale Securities, Fair Value		0			75,000
Fair Value Level 2 [Member] | Commercial Paper [Member]
Financial assets:
Available for Sale Securities, Fair Value		2,060			19,987
Fair Value Level 2 [Member] | Equity Securities [Member]
Financial assets:
Available for Sale Securities, Fair Value		0			0
Fair Value Level 3 [Member]
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and Nonfinancial Liabilities, Fair Value Disclosure		45,000			130,651
Royalty rights		351,969			402,318
Financial assets:
Assets, Fair Value		351,969			402,318
Warrants and Rights Outstanding		0
Financial liabilites:
Anniversary payment		0			88,001
Business Combination, Contingent Consideration, Liability, Noncurrent		$ 45,000			$ 42,650

[1] unaudited

[2] Note 1