Financial Instruments (Details 3) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Investments, Debt and Equity Securities [Abstract]
Proceeds from maturities and sales	$ 1,642.5	$ 601.9	$ 2,823.6	$ 975.5
Realized gains	0.6	0.3	1.0	0.5
Realized losses	$ (1.2)	$ (0.5)	$ (1.6)	$ (0.8)