Fair Values of Financial Instruments - Narrative (Details) - USD ($)
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Maturity of corporate debt with similar credit risk 20 years    
US treasury bond maturity 20 years    
Discounted cash flow, discount rate 8.67% 9.41% 9.89%
Discounted cash flow, discount rate premium 1.00%    
Institutional Products Group      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Impairment of finite-lived intangible assets     $ 13,041,000
Discounted cash flow sensitivity analysis discount rate rncrease 1.00%    
Europe      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Discounted cash flow sensitivity analysis discount rate rncrease 1.00%    
Customer lists | Institutional Products Group      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Impairment of finite-lived intangible assets     12,826,000
Noncompete Agreements | Institutional Products Group      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Impairment of finite-lived intangible assets     215,000
Foreign exchange forward      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Gain (Loss) $ 2,573,000 $ 1,112,000 $ 338,000