Fair Value Measurements (Non-Recurring) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impairment of Long-Lived Assets Held-for-use	$ 445	$ 732
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Adjustment to assets measured at fair value on non recurring basis	(1,449)	(1,953)
Fair Value, Measurements, Nonrecurring [Member] | Financing receivables and loans held for sale [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Adjustment to assets measured at fair value on non recurring basis	(317)	(361)
Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Adjustment to assets measured at fair value on non recurring basis	(372)	(466)
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets, Including Real Estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Adjustment to assets measured at fair value on non recurring basis	(760)	(1,126)
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impairment of Long-Lived Assets Held-for-use	424	2,260
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Nonrecurring [Member] | Financing receivables and loans held for sale [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impairment of Long-Lived Assets Held-for-use	49	210
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impairment of Long-Lived Assets Held-for-use	11	0
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets, Including Real Estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impairment of Long-Lived Assets Held-for-use	364	2,050
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impairment of Long-Lived Assets Held-for-use	3,075	4,720
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Financing receivables and loans held for sale [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impairment of Long-Lived Assets Held-for-use	1,430	2,986
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impairment of Long-Lived Assets Held-for-use	392	649
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets, Including Real Estate [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impairment of Long-Lived Assets Held-for-use	$ 1,253	$ 1,085