Consolidated Sponsored Investment Products (Fair Value Hierarchy Levels Of Investments Held By Consolidated Sponsored Investment Products) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Investments in Fixed Income Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	$ 15.0
Unfunded commitments	0
Redemption notice period	10 days
Investments in Other Private Equity Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	13.2
Unfunded commitments	34.2
Weighted average remaining term	8 years 6 months
Fair Value Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	88.6
Fair Value Measurements [Member] | Fixed Income Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	33.7
Fair Value Measurements [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	26.7
Fair Value Measurements [Member] | Investments in Fixed Income Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	15.0
Fair Value Measurements [Member] | Investments in Other Private Equity Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	13.2
Quoted Prices in Active Markets for Identical Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	43.3
Quoted Prices in Active Markets for Identical Assets [Member] | Fixed Income Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	2.1
Quoted Prices in Active Markets for Identical Assets [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	26.2
Quoted Prices in Active Markets for Identical Assets [Member] | Investments in Fixed Income Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	15.0
Quoted Prices in Active Markets for Identical Assets [Member] | Investments in Other Private Equity Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	0
Significant Other Observable Inputs [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	32.1
Significant Other Observable Inputs [Member] | Fixed Income Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	31.6
Significant Other Observable Inputs [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	0.5
Significant Other Observable Inputs [Member] | Investments in Fixed Income Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	0
Significant Other Observable Inputs [Member] | Investments in Other Private Equity Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	0
Significant Unobservable Inputs [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	13.2
Significant Unobservable Inputs [Member] | Fixed Income Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	0
Significant Unobservable Inputs [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	0
Significant Unobservable Inputs [Member] | Investments in Fixed Income Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	0
Significant Unobservable Inputs [Member] | Investments in Other Private Equity Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Consolidated sponsored investment products, fair value	$ 13.2