Equity Compensation Plans (Summary of Option Activity) (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Shares:
Outstanding, Beginning balance (in shares)	609,000
Granted (in shares)	91,900	131,800	75,279
Exercised (in shares)	(166,175)	(277,006)	(158,322)
Forfeited/Cancelled (in shares)	(72,000)
Outstanding, Ending balance (in shares)	463,000	609,000
Exercisable (in shares)	241,000
Expected to vest (in shares)	209,000
Weighted-Average Exercise Price:
Weighted-Average Exercise Price Outstanding, Beginning Balance (in dollars per share)	$ 14.81
Weighted-Average Exercise Price Granted (in dollars per share)	36.74
Weighted-Average Exercise Price Exercised (in dollars per share)	10.21
Weighted-Average Exercise Price Forfeited/Cancelled (in dollars per share)	19.08
Weighted-Average Exercise Price Outstanding, Ending Balance (in dollars per share)	20.15	$ 14.81
Weighted-Average Exercise Price Options Exercisable (in dollars per share)	12.37
Weighted-Average Exercise Price Expeceted to vest (in dollars per share)	$ 28.55
Weighted- Average Remaining Contractual Term (years), Outstanding	7 years 2 months 12 days
Weighted- Average Remaining Contractual Term (years), Exercisable	5 years 7 months 6 days
Weighted- Average Remaining Contractual Term (years), Expected to vest	9 years
Aggregate Intrinsic Value, Outstanding	$ 7,213
Aggregate Intrinsic Value, Exercisable	5,569
Aggregate Intrinsic Value, Expected to vest	$ 1,556