XML 184 R160.htm IDEA: XBRL DOCUMENT v3.8.0.1
Equity Based Compensation (Summary of Performance Contingent Unit Activity) (Details) - shares
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Performance Shares [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Outstanding, Number, Beginning Balance 585,971  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures 115,176  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period 137,083 94,436
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period 100,805  
Outstanding, Number, Ending Balance 463,259 585,971
Restricted Stock Units (RSUs) [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Outstanding, Number, Beginning Balance 96,628  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures 22,971  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period 38,843  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period 3,398  
Outstanding, Number, Ending Balance 77,358 96,628