Employee Postretirement Benefits (Pension Plan Assets of the Principal Plans Measured at fair value) (Details) (USD $) | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 |
In Millions, unless otherwise specified |
Projected benefit obligation (bPBOb) | $6,860 | $6,164 | |
Accumulated benefit obligation (bABOb) | 6,696 | 5,994 | |
Fair value of plan assets | 5,914 | 5,567 | |
Defined Benefit Pension [Member] | | | |
Fair value of plan assets | 5,914 | 5,567 | 5,375 |
Principal Plans [Member] | | | |
Projected benefit obligation (bPBOb) | 6,312 | 5,640 | |
Accumulated benefit obligation (bABOb) | 6,221 | 5,555 | |
Fair value of plan assets | 5,559 | 5,205 | |
Principal Plans [Member] | Fair Value, Inputs, Level 1 [Member] | | | |
Fair value of plan assets | 161 | 146 | |
Principal Plans [Member] | Fair Value, Inputs, Level 2 [Member] | | | |
Fair value of plan assets | 5,398 | 5,029 | |
Principal Plans [Member] | Fair Value, Inputs, Level 3 [Member] | | | |
Fair value of plan assets | 0 | 30 | |
Principal Plans [Member] | U.S. Equity [Member] | | | |
Fair value of plan assets | 18 | | |
Principal Plans [Member] | U.S. Equity [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 4 | 4 | |
Principal Plans [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 1 [Member] | | | |
Fair value of plan assets | 18 | | |
Principal Plans [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 1 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 4 | 4 | |
Principal Plans [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 2 [Member] | | | |
Fair value of plan assets | 0 | | |
Principal Plans [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 2 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 3 [Member] | | | |
Fair value of plan assets | 0 | | |
Principal Plans [Member] | U.S. Equity [Member] | Fair Value, Inputs, Level 3 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | Non-U.S. Equity [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 106 | 123 | |
Principal Plans [Member] | Non-U.S. Equity [Member] | Fair Value, Inputs, Level 1 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 1 | 1 | |
Principal Plans [Member] | Non-U.S. Equity [Member] | Fair Value, Inputs, Level 2 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 105 | 122 | |
Principal Plans [Member] | Non-U.S. Equity [Member] | Fair Value, Inputs, Level 3 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | International Bonds [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 1,438 | 1,089 | |
Principal Plans [Member] | International Bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | International Bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 1,438 | 1,089 | |
Principal Plans [Member] | International Bonds [Member] | Fair Value, Inputs, Level 3 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | U.S. securitized fixed income [Member] | | | |
Fair value of plan assets | 6 | 8 | |
Principal Plans [Member] | U.S. securitized fixed income [Member] | Fair Value, Inputs, Level 1 [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | U.S. securitized fixed income [Member] | Fair Value, Inputs, Level 2 [Member] | | | |
Fair value of plan assets | 6 | 8 | |
Principal Plans [Member] | U.S. securitized fixed income [Member] | Fair Value, Inputs, Level 3 [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | Cash and Cash Equivalents [Member] | | | |
Fair value of plan assets | 28 | 33 | |
Principal Plans [Member] | Cash and Cash Equivalents [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 175 | 173 | |
Principal Plans [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | | | |
Fair value of plan assets | 28 | 33 | |
Principal Plans [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 9 | 34 | |
Principal Plans [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 166 | 139 | |
Principal Plans [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | U.S. government and municipals [Member] | | | |
Fair value of plan assets | 252 | 211 | |
Principal Plans [Member] | U.S. government and municipals [Member] | Fair Value, Inputs, Level 1 [Member] | | | |
Fair value of plan assets | 71 | 71 | |
Principal Plans [Member] | U.S. government and municipals [Member] | Fair Value, Inputs, Level 2 [Member] | | | |
Fair value of plan assets | 181 | 140 | |
Principal Plans [Member] | U.S. government and municipals [Member] | Fair Value, Inputs, Level 3 [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | U.S. corporate debt [Member] | | | |
Fair value of plan assets | 2,167 | 1,654 | |
Principal Plans [Member] | U.S. corporate debt [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 149 | 186 | |
Principal Plans [Member] | U.S. corporate debt [Member] | Fair Value, Inputs, Level 1 [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | U.S. corporate debt [Member] | Fair Value, Inputs, Level 1 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | U.S. corporate debt [Member] | Fair Value, Inputs, Level 2 [Member] | | | |
Fair value of plan assets | 2,167 | 1,654 | |
Principal Plans [Member] | U.S. corporate debt [Member] | Fair Value, Inputs, Level 2 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 149 | 186 | |
Principal Plans [Member] | U.S. corporate debt [Member] | Fair Value, Inputs, Level 3 [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | U.S. corporate debt [Member] | Fair Value, Inputs, Level 3 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | Multi-sector [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 1 | 2 | |
Principal Plans [Member] | Multi-sector [Member] | Fair Value, Inputs, Level 1 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 1 | 2 | |
Principal Plans [Member] | Multi-sector [Member] | Fair Value, Inputs, Level 2 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | Multi-sector [Member] | Fair Value, Inputs, Level 3 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | Global equity [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 1,186 | 1,691 | |
Principal Plans [Member] | Global equity [Member] | Fair Value, Inputs, Level 1 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | Global equity [Member] | Fair Value, Inputs, Level 2 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 1,186 | 1,691 | |
Principal Plans [Member] | Global equity [Member] | Fair Value, Inputs, Level 3 [Member] | Mutual and Pooled Funds [Member] | | | |
Fair value of plan assets | 0 | 0 | |
Principal Plans [Member] | All Other [Member] | | | |
Fair value of plan assets | 29 | | |
Principal Plans [Member] | All Other [Member] | Fair Value, Inputs, Level 1 [Member] | | | |
Fair value of plan assets | 29 | | |
Principal Plans [Member] | Insurance Contract [Member] | | | |
Fair value of plan assets | | 30 | |
Principal Plans [Member] | Insurance Contract [Member] | Fair Value, Inputs, Level 2 [Member] | | | |
Fair value of plan assets | 0 | | |
Principal Plans [Member] | Insurance Contract [Member] | Fair Value, Inputs, Level 3 [Member] | | | |
Fair value of plan assets | 0 | 30 | |
Principal Plans [Member] | Equity - Held Through Mutual and Pooled Funds [Member] | Fair Value, Inputs, Level 1 [Member] | | | |
Fair value of plan assets | | 0 | |
Principal Plans [Member] | Equity - Held Through Mutual and Pooled Funds [Member] | Fair Value, Inputs, Level 2 [Member] | | | |
Fair value of plan assets | | 0 | |
U.S. Equity [Member] | Equity - Assets Held Directly [Member] | | | |
Fair value of plan assets | | 1 | |
U.S. Equity [Member] | Equity - Assets Held Directly [Member] | Fair Value, Inputs, Level 1 [Member] | | | |
Fair value of plan assets | | 1 | |
U.S. Equity [Member] | Equity - Assets Held Directly [Member] | Fair Value, Inputs, Level 2 [Member] | | | |
Fair value of plan assets | | 0 | |
U.S. Equity [Member] | Equity - Assets Held Directly [Member] | Fair Value, Inputs, Level 3 [Member] | | | |
Fair value of plan assets | | $0 | |