Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current:
Federal	$ 271.2	$ 322.7	$ 141.8
State	19.6	19.4	13.7
Foreign	18.6	18.5	3.1
Total current	309.4	360.6	158.6
Deferred:
Federal	117.4	(4.0)	44.3
State	(0.3)	1.2	2.3
Foreign	(0.5)	(3.0)	(0.8)
Total deferred	116.6	(5.8)	45.8
Provision	$ 426.0	$ 354.8	$ 204.4