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Share-Based Compensation - Summary of Unvested Restricted Stock Awards (Details)
12 Months Ended
Dec. 31, 2017
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]  
Unvested, beginning of period (in shares) | shares 408,162
Granted (in shares) | shares 124,126
Vested (in shares) | shares (170,434)
Forfeited (in shares) | shares (20,054)
Unvested, end of period (in shares) | shares 341,800
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]  
Unvested, beginning of period (weighted average grant date fair value) | $ / shares $ 20.47
Granted (weighted average grant date fair value) | $ / shares 33.97
Vested (weighted average grant date fair value) | $ / shares 19.97
Forfeited (weighted average grant date fair value) | $ / shares 22.09
Unvested, end of period (weighted average grant date fair value) | $ / shares $ 25.52