Income Taxes - Quarterly Disclosure (Details9) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) year	Sep. 30, 2014 USD ($)
Investments, Owned, Federal Income Tax Note [Line Items]
Income tax (provision) benefit	$ (23.4)		$ (0.5)	$ (23.7)	$ 12.4
Change in Deferred Tax Assets Valuation Allowance	63.9
Number of Years in Cumulative Loss Position | year				3
Deferred tax asset valuation allowance recorded as part of effective tax rate (percent)				6.00%
Discrete tax benefits (expense)			$ 3.4	$ (57.9)	$ 7.8
Unrecognized Tax Benefits, Period Increase (Decrease)				$ (60.9)
Federal
Investments, Owned, Federal Income Tax Note [Line Items]
Tax refund received		$ 59.9
Discrete Item
Investments, Owned, Federal Income Tax Note [Line Items]
Change in Deferred Tax Assets Valuation Allowance	56.6
Part of Effective Tax Rate [Member]
Investments, Owned, Federal Income Tax Note [Line Items]
Change in Deferred Tax Assets Valuation Allowance	$ 7.3