Income Taxes - Components of Income Tax Expense (Details 5) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current:
Federal	$ (3.4)	$ 0	$ 0
State	0.2	1.0	(2.1)
Foreign	1.9	1.9	1.8
Noncontrolling interests	0	17.6	(2.8)
Deferred:
Federal	14.0	31.5	(84.9)
State	1.2	2.8	(6.0)
Amount allocated to other comprehensive income	(22.7)	0	0
Change in valuation allowance on beginning-of-the-year deferred tax assets	(1.6)	735.2	0
Income tax expense (benefit)	$ (10.4)	$ 790.0	$ (94.0)