Corporate Investments And Funds Held For Clients (Expected Maturities Of Available-For-Sale Securities) (Details) $ in Millions	Mar. 31, 2016 USD ($)
Corporate Investments And Funds Held For Clients [Abstract]
One year or less	$ 3,317.8
One year to two years	3,023.8
Two years to three years	2,568.3
Three years to four years	4,448.2
After four years	7,681.3
Total available-for-sale securities	$ 21,039.4