Income Taxes Income Taxes, Income Tax Examination (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended				12 Months Ended
	Jan. 31, 2013 Internal Revenue Service (IRS) [Member]	Dec. 31, 2012 Internal Revenue Service (IRS) [Member]	Dec. 31, 2011 Internal Revenue Service (IRS) [Member]	Feb. 28, 2011 Internal Revenue Service (IRS) [Member]	Dec. 31, 2012 Minimum [Member] Internal Revenue Service (IRS) [Member]	Dec. 31, 2012 Minimum [Member] State and Local Jurisdiction [Member]	Dec. 31, 2012 Maximum [Member] Internal Revenue Service (IRS) [Member]	Dec. 31, 2012 Maximum [Member] State and Local Jurisdiction [Member]
Summary of income tax examinations [Abstract]
Deposits with IRS		$ 60.4	$ 52.2	$ 8.2
Refund Received Related to Revenue from Different Year, Year Revenue Recognized	42.3
Maximum decrease in unrecognized tax benefits as a result of settlement with the IRS		$ 0.6
Income tax years that remain subject to examination					2004	2002	2011	2011