Corporate Investments And Funds Held For Clients (Expected Maturities Of Available-For-Sale Securities) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012
Corporate Investments And Funds Held For Clients [Abstract]
Due in one year or less	$ 2,924.2
Due after one year to two years	1,660.4
Due after two years to three years	4,088.4
Due after three years to four years	3,883.1
Due after four years	5,860.9
Total available-for-sale securities	$ 18,417.0

Amount of debt securities categorized neither as held-to-maturity nor trading.

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