Fair Value Measurements (Non-Recurring Fair Value Measurements) (Details) - Non-recurring - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Adjustments To Assets Measured At Fair Value On Non Recurring Basis	$ (190)	$ (103)	$ (337)	$ (168)
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	0	(19)	(15)	(21)
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	(18)	(60)	(95)	(91)
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	(172)	$ (23)	(227)	$ (57)
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financing receivables and loans held for sale			0		$ 0
Cost and equity method investments	0		0		1
Long-lived assets			32		2
Assets Fair Value Disclosure	32		32		3
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financing receivables and loans held for sale			33		154
Cost and equity method investments	226		226		436
Long-lived assets			634		882
Assets Fair Value Disclosure	$ 893		$ 893		$ 1,471