Income Taxes Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended		36 Months Ended
	Sep. 30, 2013	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2012
Income Tax Examination [Line Items]
Income Tax Examination, Year under Examination		2009	2008	2010
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	$ 630
Income Tax Examination, Liability (Refund) Adjustment from Settlement with Taxing Authority	$ 135