Investments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Investment [Line Items]
Carrying Value	$ 881.3	$ 922.1
Available-for-sale securities
Investment [Line Items]
Carrying Value	654.0	611.5
Available-for-sale securities | State Street Corporation
Investment [Line Items]
Carrying Value	515.5	436.3
Available-for-sale securities | Other available-for-sale securities
Investment [Line Items]
Carrying Value	138.5	175.2
Other investments
Investment [Line Items]
Carrying Value	227.3	310.6
Trading securities | Other investments
Investment [Line Items]
Carrying Value	44.3	46.8
Held-to-maturity | Other investments
Investment [Line Items]
Carrying Value	0	14.9
Cost method, private equity and other investments | Other investments
Investment [Line Items]
Carrying Value	$ 183.0	$ 248.9