Stock-Based Compensation Plans - Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Beginning balance	939,036	1,014,420	1,220,449
Number of Shares, Granted	112,988	120,650	382
Number of Shares, Canceled	(874)		(41,071)
Number of Shares, Exercised	(195,410)	(196,034)	(165,340)
Number of Shares, Ending Balance	855,740	939,036	1,014,420
Number of Shares, Exercisable	623,076
Weighted Average Exercise Price, Beginning Balance	$ 23.83	$ 13.81	$ 15.01
Weighted Average Exercise Price, Granted	102.40	88.15	63.07
Weighted Average Exercise Price, Canceled	101.77		41.47
Weighted Average Exercise Price, Exercised	12.35	11.60	15.85
Weighted Average Exercise Price, Ending Balance	36.80	$ 23.83	$ 13.81
Weighted Average Exercise Price, Exercisable	$ 14.98
Remaining Contractual Term, Outstanding at December 31, 2016	2 years 9 months 18 days
Remaining Contractual Term, Exercisable at December 31, 2016	2 years 2 months 12 days
Intrinsic Value, Exercised	$ 21,929
Intrinsic Value, Ending Balance	94,235
Intrinsic Value, Exercisable	$ 82,208