Foreign Currency Hedging (Schedule of Effect of Derivative Instruments in Consolidated Statements of Income and Consolidated Statements of Comprehensive Income) (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Cash Flow Hedges [Member]
Derivative [Line Items]
Gain (loss) reclassified from accumulated OCI into royalty revenue, net of tax	[1]	$ 0	$ 0	$ 0	$ 1,821

[1] Effective portion classified as royalty revenue.