Fair Value Measurements (Non-Recurring Fair Value Measurements) (Details) - Non-recurring - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Adjustments To Assets Measured At Fair Value On Non Recurring Basis	$ (417)	$ (388)	$ (4,151)	$ (751)
Financing receivables and loans held for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Adjustments To Assets Measured At Fair Value On Non Recurring Basis	(46)	(31)	(2,199)	(135)
Cost and equity method investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Adjustments To Assets Measured At Fair Value On Non Recurring Basis	(280)	(82)	(1,788)	(281)
Long Lived Assets, Including Real Estate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Adjustments To Assets Measured At Fair Value On Non Recurring Basis	(91)	$ (275)	(165)	$ (335)
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost and equity method investments	1		1		$ 0
Long-lived assets, including real-estate			3		102
Financing receivables and loans held for sale			0		1
Assets Fair Value Disclosure	4		4		103
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost and equity method investments	2,347		2,347		346
Long-lived assets, including real-estate			301		718
Financing receivables and loans held for sale			18,152		584
Assets Fair Value Disclosure	$ 20,800		$ 20,800		$ 1,648