Income Taxes (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current:
Federal	$ 322.7	$ 141.8	$ (5.7)
State	19.4	13.7	7.0
Foreign	18.5	3.1	6.4
Total current	360.6	158.6	7.7
Deferred:
Federal	(4.0)	44.3	126.6
State	1.2	2.3	3.2
Foreign	(3.0)	(0.8)	(3.5)
Total deferred	(5.8)	45.8	126.3
Provision	$ 354.8	$ 204.4	$ 134.0