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Intangible Assets Schedule of changes in and the components of acquired client relationships (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Acquired client relationships [Member]
Definite-lived
Beginning balance, Gross Book Value			$ 1,039.5
Beginning balance, Accumulated Amortization			(442.8)
Beginning balance, Net Book Value			596.7
New Investments, Gross Book Value			81.5
Amortization and impairments, Gross Book Value			(27.4)
Foreign currency translation, Gross Book Value			(0.7)
Ending balance, Gross Book Value			1,120.3
Ending balance, Accumulated Amortization			(470.2)
Ending balance, Net Book Value			650.1
Indefinite-lived
Beginning balance, Net Book Value			864.0
New Investments, Net Book Value			45.4
Amortization and impairments, Net Book Value			0
Foreign currency translation, Net Book Value			1.6
Ending balance, Net Book Value			911.0
Total
Beginning balance, Net Book Value	1,561.1	1,460.7	1,460.7
New Investments, Net Book Value			126.9
Amortization and impairments, Net Book Value			(27.4)
Foreign currency translation, Net Book Value			0.9
Ending balance, Net Book Value	$ 1,561.1	$ 1,460.7	$ 1,561.1

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