Income Taxes (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2013	Dec. 31, 2012
Income Tax Expense (Benefit) [Abstract]
Net unrecognized tax benefit		$ 51.1	$ 43.9
Income tax interest and penalties accrued		0
Deferred tax assets		99.5
Effective tax rate	19.30%	(3.30%)
Income tax credits and adjustments		$ 9.4
U.S. federal statutory rate		35.00%