Annual report pursuant to Section 13 and 15(d)

Share-based Compensation - Summary of Transactions for Non-Vested Stock Options (Detail)

v3.3.1.900
Share-based Compensation - Summary of Transactions for Non-Vested Stock Options (Detail) - $ / shares
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]      
Number of Shares, Non-vested options outstanding at beginning of period 379,106 391,625 183,188
Number of Shares, Options granted 28,000 158,000 305,000
Number of Shares, Options vested (158,810) (139,602) (59,997)
Number of Shares, Options forfeited (71,608) (30,917) (36,566)
Number of Shares, Non-vested options outstanding at end of period 176,688 379,106 391,625
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]      
Weighted-Average Exercise Price Per Share, Non-vested options outstanding at beginning of period (in usd per share) $ 18.11 $ 15.56 $ 12.37
Weighted-Average Exercise Price Per Share, Options granted (in usd per share) 23.47 21.30 16.43
Weighted-Average Exercise Price Per Share, Options vested (in usd per share) 16.80 15.34 12.14
Weighted-Average Exercise Price Per Share, Options forfeited (in usd per share) 20.59 14.64 12.50
Weighted-Average Exercise Price Per Share, Non-vested options outstanding at end of period (in usd per share) $ 19.13 $ 18.11 $ 15.56