Fair Value Measurements (Non-Recurring) (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Financing receivables and loans held for sale [Member]	Mar. 31, 2012 Financing receivables and loans held for sale [Member]	Mar. 31, 2013 Cost and equity method investments [Member]	Mar. 31, 2012 Cost and equity method investments [Member]	Mar. 31, 2013 Long Lived Assets, Including Real Estate [Member]	Mar. 31, 2012 Long Lived Assets, Including Real Estate [Member]	Mar. 31, 2013 Total [Member]	Mar. 31, 2012 Total [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 2 [Member] Financing receivables and loans held for sale [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Financing receivables and loans held for sale [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 2 [Member] Cost and equity method investments [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Cost and equity method investments [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 2 [Member] Long Lived Assets, Including Real Estate [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Long Lived Assets, Including Real Estate [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 2 [Member] Total [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Total [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Financing receivables and loans held for sale [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Financing receivables and loans held for sale [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Cost and equity method investments [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Cost and equity method investments [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Long Lived Assets, Including Real Estate [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Long Lived Assets, Including Real Estate [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Total [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Total [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value assets measured on non recurring basis	$ 1,432	$ 2,412									$ 116	$ 366	$ 0	$ 8	$ 312	$ 702	$ 428	$ 1,076	$ 2,281	$ 4,094	$ 203	$ 313	$ 2,050	$ 2,182	$ 4,534	$ 6,589
Adjustments To Assets Measured At Fair Value On Non Recurring Basis			$ (128)	$ (126)	$ (72)	$ (21)	$ (359)	$ (151)	$ (559)	$ (298)