Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
Federal	$ (130.3)	$ 271.2	$ 322.7
State	3.3	19.6	19.4
Foreign	7.7	18.6	18.5
Total current	(119.3)	309.4	360.6
Deferred:
Federal	313.0	117.4	(4.0)
State	8.1	(0.3)	1.2
Foreign	0.3	(0.5)	(3.0)
Total deferred	321.4	116.6	(5.8)
Provision	$ 202.1	$ 426.0	$ 354.8