Financial Instruments (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Proceeds from Marketable Debt Securities
Proceeds from maturities and sales	$ 4,063.0	$ 2,718.9	$ 5,190.1
Realized gains	1.5	0.7	6.6
Realized losses	$ (3.5)	$ (0.5)	$ (2.1)