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Share-Based Compensation - Summary of Activity of the Outstanding Share-Based Compensation Awards (Details)
3 Months Ended
Mar. 31, 2018
$ / shares
shares
Performance Unit Incentive Plan (“PUP”)  
Summary of activity of the outstanding share-based compensation awards  
Beginning Balance, Shares | shares 239,338
Granted, Shares | shares 71,625
Vested, Shares | shares (75,761)
Forfeited, Shares | shares 0
Ending Balance, Shares | shares 235,202
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 $ 32.80
Granted, Weighted-Average Grant Date Fair Value | $ / shares 52.15
Vested, Weighted-Average Grant Date Fair Value | $ / shares 27.29
Forfeited, Weighted-Average Grant Date Fair Value | $ / shares 0
Ending Balance, Weighted-Average Grant Date Fair Value | $ / shares $ 40.46
Restricted Stock  
Summary of activity of the outstanding share-based compensation awards  
Beginning Balance, Shares | shares 206,899
Granted, Shares | shares 41,457
Vested, Shares | shares (54,458)
Forfeited, Shares | shares (1,156)
Ending Balance, Shares | shares 192,742
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 $ 33.16
Granted, Weighted-Average Grant Date Fair Value | $ / shares 52.15
Vested, Weighted-Average Grant Date Fair Value | $ / shares 27.35
Forfeited, Weighted-Average Grant Date Fair Value | $ / shares 36.37
Ending Balance, Weighted-Average Grant Date Fair Value | $ / shares $ 38.87
Restricted Stock Units  
Summary of activity of the outstanding share-based compensation awards  
Beginning Balance, Shares | shares 12,750
Granted, Shares | shares 3,669
Vested, Shares | shares (4,300)
Forfeited, Shares | shares (258)
Ending Balance, Shares | shares 11,861
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 $ 30.94
Granted, Weighted-Average Grant Date Fair Value | $ / shares 52.28
Vested, Weighted-Average Grant Date Fair Value | $ / shares 27.35
Forfeited, Weighted-Average Grant Date Fair Value | $ / shares 37.69
Ending Balance, Weighted-Average Grant Date Fair Value | $ / shares $ 38.70