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Pensions And Other Postretirement Benefits Assets and Fair Value Measurements (Details) - Pension Plan [Member] - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
--- | --- | --- | ---
U.S. [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | $ 48,215 | $ 46,329 |
Plan assets measured at net asset value | 13,522 | 14,155 |
Other plan assets (liabilities), net | 902 | 1,138 |
Net plan assets | 62,639 | 61,622 | $ 61,072
U.S. [Member] | Common and preferred stocks [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 8,911 | 8,326 |
U.S. [Member] | Government and agency debt securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 12,116 | 11,374 |
U.S. [Member] | Corporate and Other Debt Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 26,122 | 25,452 |
U.S. [Member] | Other investments, net [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 1,066 | 1,177 |
U.S. [Member] | Investment funds [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets measured at net asset value | 6,632 | 6,509 |
U.S. [Member] | Private Equity and Debt Investments [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets measured at net asset value | 3,539 | 4,012 |
U.S. [Member] | Real estate investments [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets measured at net asset value | 3,351 | 3,634 |
U.S. [Member] | Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 9,444 | 8,774 |
U.S. [Member] | Level 1 [Member] | Common and preferred stocks [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 8,892 | 8,288 |
U.S. [Member] | Level 1 [Member] | Government and agency debt securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 0 | 0 |
U.S. [Member] | Level 1 [Member] | Corporate and Other Debt Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 0 | 0 |
U.S. [Member] | Level 1 [Member] | Other investments, net [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 552 | 486 |
U.S. [Member] | Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 38,374 | 37,149 |
U.S. [Member] | Level 2 [Member] | Common and preferred stocks [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 17 | 35 |
U.S. [Member] | Level 2 [Member] | Government and agency debt securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 12,116 | 11,374 |
U.S. [Member] | Level 2 [Member] | Corporate and Other Debt Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 26,122 | 25,452 |
U.S. [Member] | Level 2 [Member] | Other investments, net [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 119 | 288 |
U.S. [Member] | Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 397 | 406 |
U.S. [Member] | Level 3 [Member] | Common and preferred stocks [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 2 | 3 |
U.S. [Member] | Level 3 [Member] | Government and agency debt securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 0 | 0 |
U.S. [Member] | Level 3 [Member] | Corporate and Other Debt Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 0 | 0 |
U.S. [Member] | Level 3 [Member] | Other investments, net [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 395 | 403 |
Non-U.S. [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 7,614 | 6,864 |
Plan assets measured at net asset value | 7,013 | 6,066 |
Other plan assets (liabilities), net | (132) | (131) |
Net plan assets | 14,495 | 12,799 | $ 12,794
Non-U.S. [Member] | Common and preferred stocks [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 585 | 981 |
Non-U.S. [Member] | Government and agency debt securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 3,853 | 3,221 |
Non-U.S. [Member] | Corporate and Other Debt Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 2,566 | 2,043 |
Non-U.S. [Member] | Other investments, net [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 610 | 619 |
Non-U.S. [Member] | Investment funds [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets measured at net asset value | 5,346 | 4,428 |
Non-U.S. [Member] | Private Equity and Debt Investments [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets measured at net asset value | 570 | 546 |
Non-U.S. [Member] | Real estate investments [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets measured at net asset value | 1,097 | 1,092 |
Non-U.S. [Member] | Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 601 | 1,015 |
Non-U.S. [Member] | Level 1 [Member] | Common and preferred stocks [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 578 | 978 |
Non-U.S. [Member] | Level 1 [Member] | Government and agency debt securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 0 | 0 |
Non-U.S. [Member] | Level 1 [Member] | Corporate and Other Debt Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 0 | 0 |
Non-U.S. [Member] | Level 1 [Member] | Other investments, net [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 23 | 37 |
Non-U.S. [Member] | Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 6,569 | 5,417 |
Non-U.S. [Member] | Level 2 [Member] | Common and preferred stocks [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 1 | 3 |
Non-U.S. [Member] | Level 2 [Member] | Government and agency debt securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 3,853 | 3,221 |
Non-U.S. [Member] | Level 2 [Member] | Corporate and Other Debt Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 2,566 | 2,040 |
Non-U.S. [Member] | Level 2 [Member] | Other investments, net [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 149 | 153 |
Non-U.S. [Member] | Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 444 | 432 |
Non-U.S. [Member] | Level 3 [Member] | Common and preferred stocks [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 6 | 0 |
Non-U.S. [Member] | Level 3 [Member] | Government and agency debt securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 0 | 0 |
Non-U.S. [Member] | Level 3 [Member] | Corporate and Other Debt Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | 0 | 3 |
Non-U.S. [Member] | Level 3 [Member] | Other investments, net [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net plan assets subject to leveling | $ 438 | $ 429 |

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