Fair Value Measurements (Significant Unobservable Inputs) (Details) (Level 3, USD $) | 3 Months Ended | 12 Months Ended | | |
In Millions, unless otherwise specified | Mar. 31, 2015 | Dec. 31, 2014 | Mar. 31, 2014 | Dec. 31, 2013 |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 2,679 | 2,600 | | |
Assets Fair Value Disclosure Nonrecurring | 3,741 | 844 | | |
Individually Insignificant Recurring Fair Value Measurements | 94 | 261 | | |
Individually Insignificant NonRecurring Fair Value Measurements | 53 | 108 | | |
Recurring | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 4,881 | 12,390 | 11,833 | 11,510 |
Recurring | US Corporate | Income Approach | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Investments, Fair Value Disclosure | 1,015 | 980 | | |
Recurring | US Corporate | Income Approach | Lower Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 1.70% | 1.50% | | |
Recurring | US Corporate | Income Approach | Upper Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 13.20% | 14.80% | | |
Recurring | US Corporate | Income Approach | Weighted Average | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 6.70% | 6.60% | | |
Recurring | State And Municipal Debt | Income Approach | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Investments, Fair Value Disclosure | 456 | 481 | | |
Recurring | State And Municipal Debt | Income Approach | Lower Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 2.80% | 1.90% | | |
Recurring | State And Municipal Debt | Income Approach | Upper Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 6.30% | 5.90% | | |
Recurring | State And Municipal Debt | Income Approach | Weighted Average | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 4.80% | 2.80% | | |
Recurring | Asset-backed | Income Approach | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Investments, Fair Value Disclosure | 99 | 7,554 | | |
Recurring | Asset-backed | Income Approach | Lower Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 5.30% | 2.20% | | |
Recurring | Asset-backed | Income Approach | Upper Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 9.00% | 12.40% | | |
Recurring | Asset-backed | Income Approach | Weighted Average | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 5.60% | 5.00% | | |
Recurring | Corporate - non-U.S. | Income Approach | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Investments, Fair Value Disclosure | 333 | 388 | | |
Recurring | Corporate - non-U.S. | Income Approach | Lower Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 0.20% | 0.40% | | |
Recurring | Corporate - non-U.S. | Income Approach | Upper Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 14.00% | 14.00% | | |
Recurring | Corporate - non-U.S. | Income Approach | Weighted Average | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 5.60% | 5.70% | | |
Recurring | Other financial assets | Income Approach | Lower Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 6.50% | | | |
WACC | | 5.40% | | |
Recurring | Other financial assets | Income Approach | Upper Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 7.80% | | | |
WACC | | 9.10% | | |
Recurring | Other financial assets | Income Approach | Weighted Average | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 7.70% | | | |
WACC | | 7.70% | | |
Recurring | Other financial assets | Market comparables | Lower Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
EBITDA Multiple | 1.5 | 5.4 | | |
Recurring | Other financial assets | Market comparables | Upper Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
EBITDA Multiple | 9 | 7.8 | | |
Recurring | Other financial assets | Market comparables | Weighted Average | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
EBITDA Multiple | 6.5 | 5.7 | | |
Recurring | Other financial assets | Income Approach, Market Comparables | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Investments, Fair Value Disclosure | 195 | 117 | | |
Non-recurring | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Assets Fair Value Disclosure Nonrecurring | 46,146 | 2,043 | | |
Non-recurring | Financing receivables and loans held for sale | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Assets Fair Value Disclosure Nonrecurring | 41,644 | 808 | | |
Non-recurring | Financing receivables and loans held for sale | Income Approach | Lower Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Capitalization Rate | 1.00% | 4.30% | | |
Non-recurring | Financing receivables and loans held for sale | Income Approach | Upper Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Capitalization Rate | 30.00% | 6.50% | | |
Non-recurring | Financing receivables and loans held for sale | Income Approach | Weighted Average | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Capitalization Rate | 11.00% | 6.20% | | |
Non-recurring | Financing receivables and loans held for sale | Business Enterprise Value | Lower Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
EBITDA Multiple | 1.5 | | | |
Non-recurring | Financing receivables and loans held for sale | Business Enterprise Value | Upper Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
EBITDA Multiple | 0 | | | |
Non-recurring | Financing receivables and loans held for sale | Business Enterprise Value | Weighted Average | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
EBITDA Multiple | 6.5 | | | |
Non-recurring | Financing receivables and loans held for sale | Income Approach, Business Enterprise value | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Investments, Fair Value Disclosure | 40,043 | 82 | | |
Non-recurring | Cost and equity method investments | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Assets Fair Value Disclosure Nonrecurring | | 399 | | |
Non-recurring | Cost and equity method investments | Income Approach | Lower Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 0.40% | 8.00% | | |
Capitalization Rate | | 1.80% | | |
Non-recurring | Cost and equity method investments | Income Approach | Upper Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 0.00% | 10.00% | | |
Capitalization Rate | | 10.50% | | |
Non-recurring | Cost and equity method investments | Income Approach | Weighted Average | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 0.00% | 9.40% | | |
Capitalization Rate | | 7.00% | | |
Non-recurring | Cost and equity method investments | Income Approach, Market Comparables | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Investments, Fair Value Disclosure | | 343 | | |
Non-recurring | Cost and equity method investments | Income Approach, Business Enterprise Value, Market Comparable | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Investments, Fair Value Disclosure | 1,928 | | | |
Non-recurring | Cost and equity method investments | Business Enterprise Value, Market Comparables | Lower Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Capitalization Rate | 0.00% | | | |
Non-recurring | Cost and equity method investments | Business Enterprise Value, Market Comparables | Upper Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Capitalization Rate | 0.00% | | | |
Non-recurring | Cost and equity method investments | Business Enterprise Value, Market Comparables | Weighted Average | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Capitalization Rate | 0.00% | | | |
Non-recurring | Long Lived Assets, Including Real Estate | Income Approach | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Investments, Fair Value Disclosure | 381 | 666 | | |
Non-recurring | Long Lived Assets, Including Real Estate | Income Approach | Lower Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 0.00% | 0.00% | | |
Capitalization Rate | 4.50% | 2.00% | | |
Non-recurring | Long Lived Assets, Including Real Estate | Income Approach | Upper Limit | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 0.00% | 0.00% | | |
Capitalization Rate | 15.40% | 19.00% | | |
Non-recurring | Long Lived Assets, Including Real Estate | Income Approach | Weighted Average | | | | |
Fair Value, Assets Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Line Items] | | | | |
Discount Rate | 0.00% | 0.00% | | |
Capitalization Rate | 0.00% | 6.80% | | |