XML 81 R66.htm IDEA: XBRL DOCUMENT v3.8.0.1
Share-Based Compensation - Incentive Unit Awards (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Liability for unvested restricted share awards $ 55.9 $ 45.7  
Incentive Unit Award      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 3 years    
Number of shares considered for determining cash payment for each award upon vesting (in shares) 1    
Unrecognized compensation cost $ 10.0    
Weighted-average period for amortization of unrecognized compensation cost 1 year 7 months    
Compensation expense $ 6.8 2.3 $ 5.7
Cash paid to settle liability-classified awards upon vesting $ 5.5 3.0 $ 3.9
Incentive Unit Award | Tranche One      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting percentage 33.33%    
Incentive Unit Award | Tranche Two      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting percentage 33.33%    
Incentive Unit Award | Tranche Three      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting percentage 33.33%    
Personnel Accruals | Incentive Unit Award      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Liability for unvested restricted share awards $ 3.3 $ 1.9