Corporate Investments And Funds Held For Clients (Expected Maturities Of Available-For-Sale Securities) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015
Corporate Investments And Funds Held For Clients [Abstract]
One year or less	$ 4,569.1
One year to two years	3,414.2
Two years to three years	3,037.6
Three years to four years	2,360.9
After four years	7,159.7
Total available-for-sale securities	$ 20,541.5