Fair Value Measurements (Non-Recurring Measurement) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2012
Financing receivables and loans held for sale [Member] | Income Approach Valuation Technique [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%
Financing receivables and loans held for sale [Member] | Income Approach Valuation Technique [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	5.40%
Financing receivables and loans held for sale [Member] | Income Approach Valuation Technique [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	11.50%
Cost and equity method investments [Member] | Income Approach Valuation Technique [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	8.30%
Cost and equity method investments [Member] | Income Approach Valuation Technique [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	7.00%
Cost and equity method investments [Member] | Income Approach Valuation Technique [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	9.30%
Long Lived Assets, Including Real Estate [Member] | Income Approach Valuation Technique [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	7.40%
Long Lived Assets, Including Real Estate [Member] | Income Approach Valuation Technique [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%
Long Lived Assets, Including Real Estate [Member] | Income Approach Valuation Technique [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	11.00%
Domestic Corporate Debt Securities [Member] | Income Approach Valuation Technique [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Weighted Average Discount Rate Used For Level Three Valuation	10.60%
Domestic Corporate Debt Securities [Member] | Income Approach Valuation Technique [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	2.00%
Domestic Corporate Debt Securities [Member] | Income Approach Valuation Technique [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	24.90%
Asset-backed Securities [Member] | Income Approach Valuation Technique [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Weighted Average Discount Rate Used For Level Three Valuation	4.20%
Asset-backed Securities [Member] | Income Approach Valuation Technique [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%
Asset-backed Securities [Member] | Income Approach Valuation Technique [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%
Foreign Corporate Debt Securities [Member] | Income Approach Valuation Technique [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Weighted Average Discount Rate Used For Level Three Valuation	8.30%
Foreign Corporate Debt Securities [Member] | Income Approach Valuation Technique [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%
Foreign Corporate Debt Securities [Member] | Income Approach Valuation Technique [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	30.20%
Fair Value, Measurements, Recurring [Member] | Other [Member] | Market Comparables Valuation Technique [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Weighted Average Cost Of Capital Used For Level Three Valuation	8.30%
Fair Value, Measurements, Recurring [Member] | Other [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	7.60%
Fair Value, Measurements, Recurring [Member] | Other [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	8.30%
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Domestic Corporate Debt Securities [Member] | Cost and equity method investments [Member] | Income Approach Valuation Technique [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	1,547
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member] | Cost and equity method investments [Member] | Income Approach Valuation Technique [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	4,259
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Corporate Debt Securities [Member] | Cost and equity method investments [Member] | Income Approach Valuation Technique [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	912
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member] | Cost and equity method investments [Member] | Market Comparables Valuation Technique [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	367
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Financing receivables and loans held for sale [Member] | Income Approach Valuation Technique [Member] | Capitalization Rate Unobservable Inputs [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	1,828
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Cost and equity method investments [Member] | Income Approach Valuation Technique [Member] | Capitalization Rate Unobservable Inputs [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	119
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Long Lived Assets, Including Real Estate [Member] | Income Approach Valuation Technique [Member] | Capitalization Rate Unobservable Inputs [Member]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	441