Fair Value Measurements (Significant Unobservable Input) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Jun. 30, 2015	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
Lower Limit
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	10.40%
Maximum [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	11.00%
Fair Value, Measurements, Recurring
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	$ 97	$ 295
Fair Value, Inputs, Level 3
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair Value, Measurement Recurring Basis, Asset Value	2,689	2,594
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	38	123
Fair Value, Measurement Recurring Basis, Asset Value	3,842	3,948	$ 3,855	$ 4,063	$ 4,130	$ 3,878
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Income Approach [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	38
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Domestic Corporate Debt Securities [Member] | Income Approach [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	$ 863	$ 917
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Domestic Corporate Debt Securities [Member] | Income Approach [Member] | Lower Limit
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	2.20%	1.50%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Domestic Corporate Debt Securities [Member] | Income Approach [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	15.30%	14.80%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Domestic Corporate Debt Securities [Member] | Income Approach [Member] | Weighted Average [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	7.40%	6.60%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Asset-backed Securities [Member] | Income Approach [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure		$ 102
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Asset-backed Securities [Member] | Income Approach [Member] | Lower Limit
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	5.00%	4.30%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Asset-backed Securities [Member] | Income Approach [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	10.00%	9.00%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Asset-backed Securities [Member] | Income Approach [Member] | Weighted Average [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	9.10%	5.60%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Foreign Corporate Debt Securities [Member] | Income Approach [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	$ 226	$ 278
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Foreign Corporate Debt Securities [Member] | Income Approach [Member] | Lower Limit
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	6.50%	3.30%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Foreign Corporate Debt Securities [Member] | Income Approach [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	14.00%	14.00%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Foreign Corporate Debt Securities [Member] | Income Approach [Member] | Weighted Average [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	7.40%	6.50%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | State And Municipal Debt Securities [Member] | Income Approach [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure		$ 17
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | State And Municipal Debt Securities [Member] | Income Approach [Member] | Lower Limit
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate		4.90%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | State And Municipal Debt Securities [Member] | Income Approach [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate		4.90%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | State And Municipal Debt Securities [Member] | Income Approach [Member] | Weighted Average [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate		4.90%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Other 1 [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Individually Insignificant Recurring Fair Value Measurements	$ 14	$ 30
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Financing receivables and loans held for sale [Member] | Income Approach [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair value measurments - nonrecurring	$ 18,015
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Financing receivables and loans held for sale [Member] | Income Approach [Member] | Lower Limit
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	5.60%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Financing receivables and loans held for sale [Member] | Income Approach [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	8.00%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Financing receivables and loans held for sale [Member] | Income Approach [Member] | Weighted Average [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	6.70%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Income Approach [Member] | Lower Limit
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate		8.00%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Income Approach [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate		10.00%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Income Approach [Member] | Weighted Average [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate		9.40%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Market Comparables [Member] | Lower Limit
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
EBITDA Multiple		1.8
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Market Comparables [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
EBITDA Multiple		5.2
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Market Comparables [Member] | Weighted Average [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
EBITDA Multiple		4.8
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Income Approach, Market Comparables [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	$ 2,134	$ 309
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Income Approach, Market Comparables [Member] | Lower Limit
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	9.00%
Price to book multiple	0.4
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Income Approach, Market Comparables [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	14.50%
Price to book multiple	0.7
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Income Approach, Market Comparables [Member] | Weighted Average [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	11.80%
Price to book multiple	0.6
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets, Including Real Estate [Member] | Income Approach [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair value measurments - nonrecurring	$ 198	$ 664
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets, Including Real Estate [Member] | Income Approach [Member] | Lower Limit
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	1.70%	2.00%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets, Including Real Estate [Member] | Income Approach [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	9.80%	10.80%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets, Including Real Estate [Member] | Income Approach [Member] | Weighted Average [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Discount Rate	6.20%	6.70%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring [Member] | Other 1 [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Fair value measurments - nonrecurring	$ 267	$ 657
Individually Insignificant NonRecurring Fair Value Measurements	$ 171	$ 6