Income Taxes - Textual (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended				1 Months Ended			12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Apr. 30, 2013 Federal [Member]	Dec. 31, 2013 Federal [Member]	Dec. 31, 2013 State [Member]	Dec. 31, 2012 Deferred Tax Asset, Valuation Allowance, Realizable in Future [Member]	Dec. 31, 2011 Deferred Tax Asset, Valuation Allowance Decrease, Corrections [Member]	Dec. 31, 2011 Deferred Tax Asset, Valuation Allowance Decrease, I R S Settlement [Member]
Income Taxes (Textual) [Abstract]
Income Tax Benefit Resulting From Tax Settlement			$ 18		$ 115
Increase Net Operating Loss Carryforward, Gross					283
Net Reduction in Valuation Allowance			28
Adjustment to Income Tax Expense, Prior Year Corrections			7
Net Operating Loss Carryforwards	416.5	432.5				325.1	91.4
Gross Operating Loss Carryforwards	929.0
Excess Tax Benefit from Share-based Compensation	8.6
Deferred Tax Assets, Valuation Allowance, Decrease	9.1	10.5	62.4					21.0	34.0	7.0
Valuation Allowance	30.7	39.8
Gross Unrecognized Tax Benefits	1.1	78.0	6.0	12.6
Unrecognized Tax Benefits, Accrued Interest	0.3	0	0.1	1.1
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	0.4	76.0
Interest Income Included in Income Tax Expense	(0.2)	(0.7)	(4.7)
Total Accrued Interest (Expense) Income Related to Income Tax Matters	$ 0.1	$ (0.2)