Fair Value Measurements (Non-Recurring Measurement) (Details) (Fair Value, Inputs, Level 3 [Member], USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Fair Value, Measurements, Recurring [Member] | Domestic Corporate Debt Securities [Member] | Income Approach Valuation Techniques [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	$ 1,579
Weighted Average Discount Rate Used For Level Three Valuation	10.80%
Fair Value, Measurements, Recurring [Member] | Domestic Corporate Debt Securities [Member] | Income Approach Valuation Techniques [Member] | Lower Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Range Discount Rate Used For Level Three Valuation	1.60%
Fair Value, Measurements, Recurring [Member] | Domestic Corporate Debt Securities [Member] | Income Approach Valuation Techniques [Member] | Upper Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Range Discount Rate Used For Level Three Valuation	28.80%
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member] | Income Approach Valuation Techniques [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	4,773
Weighted Average Discount Rate Used For Level Three Valuation	3.50%
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member] | Income Approach Valuation Techniques [Member] | Lower Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Range Discount Rate Used For Level Three Valuation	1.30%
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member] | Income Approach Valuation Techniques [Member] | Upper Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Range Discount Rate Used For Level Three Valuation	13.30%
Fair Value, Measurements, Recurring [Member] | Foreign Corporate Debt Securities [Member] | Income Approach Valuation Techniques [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	922
Weighted Average Discount Rate Used For Level Three Valuation	12.20%
Fair Value, Measurements, Recurring [Member] | Foreign Corporate Debt Securities [Member] | Income Approach Valuation Techniques [Member] | Lower Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Range Discount Rate Used For Level Three Valuation	0.20%
Fair Value, Measurements, Recurring [Member] | Foreign Corporate Debt Securities [Member] | Income Approach Valuation Techniques [Member] | Upper Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Range Discount Rate Used For Level Three Valuation	29.70%
Fair Value, Measurements, Recurring [Member] | Other 1 [Member] | Market Comparables Valuation Technique [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	398
Weighted Average Cost Of Capital Used For Level Three Valuation	9.30%
Fair Value, Measurements, Recurring [Member] | Other 1 [Member] | Market Comparables Valuation Technique [Member] | Lower Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Weighted Average Cost Of Capital Used For Level Three Valuation	9.20%
Fair Value, Measurements, Recurring [Member] | Other 1 [Member] | Market Comparables Valuation Technique [Member] | Upper Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Weighted Average Cost Of Capital Used For Level Three Valuation	10.90%
Fair Value, Measurements, Nonrecurring [Member] | Financing receivables and loans held for sale [Member] | Income Approach Valuation Techniques [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	2,382
Weighted Average Capitalization Rate Used For Level Three Valuation	8.40%
Fair Value, Measurements, Nonrecurring [Member] | Financing receivables and loans held for sale [Member] | Income Approach Valuation Techniques [Member] | Lower Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Range Capitalization Rate Used For Level Three Valuation	5.40%
Fair Value, Measurements, Nonrecurring [Member] | Financing receivables and loans held for sale [Member] | Income Approach Valuation Techniques [Member] | Upper Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Range Capitalization Rate Used For Level Three Valuation	27.90%
Fair Value, Measurements, Nonrecurring [Member] | Financing receivables and loans held for sale [Member] | Business Enterprise Value Valuation Technique [Member] | EBITDA Multiple [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	225
Weighted Average EBITDA Multiple Used For Level Three Valuation	4.6
Fair Value, Measurements, Nonrecurring [Member] | Financing receivables and loans held for sale [Member] | Business Enterprise Value Valuation Technique [Member] | EBITDA Multiple [Member] | Lower Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Range EBITDA Multiple Used For Level Three Valuation	4.0
Fair Value, Measurements, Nonrecurring [Member] | Financing receivables and loans held for sale [Member] | Business Enterprise Value Valuation Technique [Member] | EBITDA Multiple [Member] | Upper Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Range EBITDA Multiple Used For Level Three Valuation	6.9
Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Income Approach Valuation Techniques [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	99
Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Income Approach Valuation Techniques [Member] | Capitalization Rate Unobservable Inputs [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Weighted Average Capitalization Rate Used For Level Three Valuation	9.20%
Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Income Approach Valuation Techniques [Member] | Capitalization Rate Unobservable Inputs [Member] | Lower Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Range Capitalization Rate Used For Level Three Valuation	8.60%
Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Income Approach Valuation Techniques [Member] | Capitalization Rate Unobservable Inputs [Member] | Upper Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Range Capitalization Rate Used For Level Three Valuation	12.80%
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets, Including Real Estate [Member] | Income Approach Valuation Techniques [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	$ 764
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets, Including Real Estate [Member] | Income Approach Valuation Techniques [Member] | Capitalization Rate Unobservable Inputs [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Weighted Average Capitalization Rate Used For Level Three Valuation	8.20%
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets, Including Real Estate [Member] | Income Approach Valuation Techniques [Member] | Capitalization Rate Unobservable Inputs [Member] | Lower Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Range Capitalization Rate Used For Level Three Valuation	4.80%
Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets, Including Real Estate [Member] | Income Approach Valuation Techniques [Member] | Capitalization Rate Unobservable Inputs [Member] | Upper Limit [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Range Capitalization Rate Used For Level Three Valuation	14.60%