Segment Information - Segment Description (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Diversified industrial        
Segment Reporting Information [Line Items]        
Management Fees Revenue $ 2,900 $ 2,689 $ 8,813 $ 7,443
Energy        
Segment Reporting Information [Line Items]        
Management Fees Revenue 2,000 2,038 6,113 6,113
Financial services        
Segment Reporting Information [Line Items]        
Management Fees Revenue $ 1,175 $ 563 $ 3,525 $ 1,688