Consolidated Sponsored Investment Products (NAV as practical expedient) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investments, Consolidated Sponsored Investment Products, Fair Value Disclosure	$ 290.3
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investments, Consolidated Sponsored Investment Products, Fair Value Disclosure	0.7
Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investments, Consolidated Sponsored Investment Products, Fair Value Disclosure	0.0
Fixed Income Funds [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investments, Consolidated Sponsored Investment Products, Fair Value Disclosure	$ 35.0
Redemption notice period	10 days
Fixed Income Funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investments, Consolidated Sponsored Investment Products, Fair Value Disclosure	$ 0.0
Fixed Income Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investments, Consolidated Sponsored Investment Products, Fair Value Disclosure	0.0
Fixed Income Funds [Member] | Priced Using NAV Practical Expedient [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investments, Consolidated Sponsored Investment Products, Fair Value Disclosure	35.0
Investments, Consolidated Sponsored Investment Products, Unfunded Commitments	0.0
Private Equity Funds [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investments, Consolidated Sponsored Investment Products, Fair Value Disclosure	$ 50.4
Weighted average remaining term	7 years 10 months 24 days
Private Equity Funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investments, Consolidated Sponsored Investment Products, Fair Value Disclosure	$ 0.0
Private Equity Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investments, Consolidated Sponsored Investment Products, Fair Value Disclosure	0.0
Private Equity Funds [Member] | Priced Using NAV Practical Expedient [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Investments, Consolidated Sponsored Investment Products, Fair Value Disclosure	50.4
Investments, Consolidated Sponsored Investment Products, Unfunded Commitments	$ 33.2