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Equity-Based Compensation - SARs Additional Information (Details) - SARs - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 4 years    
Number of SARs exercisable (in shares) 306,575 281,221 453,781
SARs exercisable weighted average price per share (in dollars per share) $ 11.28 $ 11.46 $ 10.67
Aggregate intrinsic value of SARs outstanding $ 1,327 $ 800 $ 600
First anniversary of grant date      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting percentage 25.00%    
Vest ratably each month over the subsequent 36 months      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 36 months    
Vesting percentage 75.00%