Stock-Based Compensation Plans - Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Beginning balance	1,014,420	1,220,449	1,429,822
Number of Shares, Granted	120,650	382	51,597
Number of Shares, Canceled		(41,071)	(4,348)
Number of Shares, Exercised	(196,034)	(165,340)	(256,622)
Number of Shares, Ending Balance	939,036	1,014,420	1,220,449
Number of Shares, Exercisable	790,471
Weighted Average Exercise Price, Beginning Balance	$ 13.81	$ 15.01	$ 13.62
Weighted Average Exercise Price, Granted	88.15	63.07	41.75
Weighted Average Exercise Price, Canceled		41.47	33.84
Weighted Average Exercise Price, Exercised	11.60	15.85	12.33
Weighted Average Exercise Price, Ending Balance	23.83	$ 13.81	$ 15.01
Weighted Average Exercise Price, Exercisable	$ 14.07
Remaining contractual term, Outstanding at December 31, 2013	2 years 10 months 24 days
Remaining contractual term, Exercisable at December 31, 2014	2 years 7 months 6 days
Intrinsic Value, Exercised	$ 15,312
Intrinsic Value, Ending Balance	82,412
Intrinsic Value, Exercisable	$ 77,084