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Equity In Net Assets Of Nonconsolidated Affiliates (Details) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 USD ($) joint_venture | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($)
Schedule of Equity Method Investments [Line Items] |  |  |
Equity income | $ 2,132 | $ 2,282 | $ 2,193
Equity Method Investments | 9,073 | 8,996 | 9,195
Basis Difference | $ 4,300 | 4,300 |
Number of joint ventures engaged in production, import and sale of products | joint_venture | 4 |  |
SGM [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Number of interests in other joint ventures | joint_venture | 3 |  |
Automotive China [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Equity income | $ 1,976 | 1,973 | 2,057
Equity Method Investments | 7,832 | 7,859 |
Other joint ventures [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Equity income | 156 | 309 | $ 136
Equity Method Investments | $ 1,241 | $ 1,137 |
SGM [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 50.00% | 50.00% |
SGM [Member] | SAIC [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 50.00% |  |
FAW-GM [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 50.00% | 50.00% |
PATAC [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 50.00% | 50.00% |
SGMS [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 49.00% | 49.00% |
SGMW [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 44.00% | 44.00% |
Shanghai OnStar [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 40.00% | 40.00% |
Shanghai OnStar [Member] | SGM [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 20.00% |  |
SGM Norsom [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 25.00% | 25.00% |
SGM Norsom [Member] | SGM [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage |  | 50.00% |
SGM Norsom [Member] | SAIC [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage |  | 25.00% |
SGM DY [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 25.00% | 25.00% |
SGM DY [Member] | SGM [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage |  | 50.00% |
SGM DY [Member] | SAIC [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage |  | 25.00% |
SGM DYPT [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 25.00% | 25.00% |
SGM DYPT [Member] | SGM [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage |  | 50.00% |
SGM DYPT [Member] | SAIC [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage |  | 25.00% |
Shanghai Chengxin [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 0.00% | 33.00% |
SAIC-GMAC [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 35.00% | 35.00% |
SAIC-GMAC [Member] | SGM [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 20.00% |  |
SAIC-GMAC [Member] | Shanghai Automotive Group Finance Company Ltd. [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 45.00% |  |
SGM Norsom, SGM DY and SGM DYPT [Member] | SGM [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 50.00% |  |
SGM Norsom, SGM DY and SGM DYPT [Member] | SAIC [Member] |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Ownership Percentage | 25.00% |  |

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