Stockholders' Equity (Restricted Stock Units Activity) (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restricted Stock Units (RSUs) [Member]
Schedule of Share based Compensation Arrangements by Share based Payment Award, Equity Instruments, Other Than Options, Restricted Stock Units [Line Items]
Restricted stock units granted	332,782	504,255	574,017
Weighted average grant-date fair value of award	$ 45.13	$ 42.54	$ 34.06
Total fair value of restricted stock units granted	$ 15,019	$ 21,449	$ 19,550
Restricted stock units becoming free of restrictions	478,686	563,117	543,921
Weighted average restriction period (in years)	3 years 10 months 24 days	3 years 10 months 24 days	3 years 10 months 24 days
Performance Shares [Member]
Schedule of Share based Compensation Arrangements by Share based Payment Award, Equity Instruments, Other Than Options, Restricted Stock Units [Line Items]
Restricted stock units granted	238,690
Weighted average grant-date fair value of award	$ 44.96