Income Taxes, Income Tax Examination (Details) (USD $) In Millions, unless otherwise specified				9 Months Ended
	Sep. 30, 2013 Internal Revenue Service (IRS) [Member]	Jan. 31, 2013 Internal Revenue Service (IRS) [Member]	Dec. 31, 2012 Internal Revenue Service (IRS) [Member]	Sep. 30, 2013 Internal Revenue Service (IRS) [Member] Minimum [Member]	Sep. 30, 2013 Internal Revenue Service (IRS) [Member] Maximum [Member]	Sep. 30, 2013 State and Local Jurisdiction [Member] Minimum [Member]	Sep. 30, 2013 State and Local Jurisdiction [Member] Maximum [Member]
Income Tax Examination [Line Items]
Tax years that remain subject to examination				2007	2012	2002	2011
Summary of income tax examinations [Abstract]
Deposits with the IRS			$ 60.4
Deposits with the IRS remaining to offset tax and interest liabilities			43.5
Refund adjustment from settlement with taxing authority		42.3
Income tax years currently under examination				2010	2012
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Upper Bound	$ (4.6)