Foreign Currency Hedging (Schedule of Effect of Derivative Instruments in Consolidated Statements of Income and Consolidated Statements of Comprehensive Income) (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Net gain (loss) recognized in OCI, net of tax	[1]	$ 0	$ 0	$ 0
Gain (loss) reclassified from accumulated OCI into royalty revenue, net of tax	[2]	$ 0	$ 0	$ 1,821

[1] (1) Net change in the fair value of the effective portion of cash flow hedges classified in Other Comprehensive Income

[2] (2) Effective portion classified as royalty revenue