Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation - Schedule of Restricted Stock Awards (Detail)

v3.7.0.1
Share-Based Compensation - Schedule of Restricted Stock Awards (Detail) - Restricted stock awards [Member] - $ / shares
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Vesting period   3 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]    
Number of Shares, Restricted stock at beginning of period 336,455 343,958
Number of Shares, Restricted stock granted 3,761 91,006
Number of Shares, Restricted stock vested (30,430) (119,344)
Number of Shares, Restricted stock forfeited (3,835) (9,669)
Number of Shares, Restricted stock at end of period 305,951 305,951
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]    
Weighted-Average Grant Date Fair Value Per Share, Restricted stock at beginning of period (in usd per share) $ 20.39 $ 16.60
Weighted-Average Grant Date Fair Value Per Share, Restricted stock granted (in usd per share) 28.91 31.36
Weighted-Average Grant Date Fair Value Per Share, Restricted stock vested (in usd per share) 22.62 18.07
Weighted-Average Grant Date Fair Value Per Share, Restricted stock forfeited (in usd per share) 25.25 23.26
Weighted-Average Grant Date Fair Value Per Share, Restricted stock at end of period (in usd per share) $ 20.21 $ 20.21