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Share-Based Compensation - Summary of Activity of the Outstanding Share-Based Compensation Awards (Details)
12 Months Ended
Dec. 31, 2017
$ / shares
shares
Performance Unit Incentive Plan (“PUP”)  
Summary of activity of the outstanding share-based compensation awards  
Beginning Balance, Shares | shares 255,505
Granted, Shares | shares 73,557
Vested, Shares | shares (76,082)
Forfeited, Shares | shares (13,642)
Ending Balance, Shares | shares 239,338
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]  
Beginning Balance, Weighted-Average Grant Date Fair Value | $ / shares $ 26.11
Granted, Weighted-Average Grant Date Fair Value | $ / shares 47.44
Vested, Weighted-Average Grant Date Fair Value | $ / shares 24.07
Forfeited, Weighted-Average Grant Date Fair Value | $ / shares 34.99
Ending Balance, Weighted-Average Grant Date Fair Value | $ / shares $ 32.80
Restricted Stock  
Summary of activity of the outstanding share-based compensation awards  
Beginning Balance, Shares | shares 267,051
Granted, Shares | shares 67,029
Vested, Shares | shares (112,548)
Forfeited, Shares | shares (14,633)
Ending Balance, Shares | shares 206,899
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]  
Beginning Balance, Weighted-Average Grant Date Fair Value | $ / shares $ 25.96
Granted, Weighted-Average Grant Date Fair Value | $ / shares 46.99
Vested, Weighted-Average Grant Date Fair Value | $ / shares 24.04
Forfeited, Weighted-Average Grant Date Fair Value | $ / shares 35.31
Ending Balance, Weighted-Average Grant Date Fair Value | $ / shares $ 33.16
Restricted Stock Units  
Summary of activity of the outstanding share-based compensation awards  
Beginning Balance, Shares | shares 15,982
Granted, Shares | shares 2,950
Vested, Shares | shares (6,182)
Forfeited, Shares | shares 0
Ending Balance, Shares | shares 12,750
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]  
Beginning Balance, Weighted-Average Grant Date Fair Value | $ / shares $ 25.58
Granted, Weighted-Average Grant Date Fair Value | $ / shares 47.45
Vested, Weighted-Average Grant Date Fair Value | $ / shares 24.97
Forfeited, Weighted-Average Grant Date Fair Value | $ / shares 0
Ending Balance, Weighted-Average Grant Date Fair Value | $ / shares $ 30.94