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Equity In Net Assets Of Nonconsolidated Affiliates (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) joint_venture	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Schedule of Equity Method Investments [Line Items]
Equity income	$ 674	$ 1,268	$ 2,163
Equity in net assets of nonconsolidated affiliates	8,406	8,562	9,215
Basis Difference	$ 4,200	4,200
Number of joint ventures engaged in production, import and sale of products | joint_venture	4
SGM
Schedule of Equity Method Investments [Line Items]
Number of interests in other joint ventures | joint_venture	3
Automotive China
Schedule of Equity Method Investments [Line Items]
Equity income	$ 512	1,132	1,981
Equity in net assets of nonconsolidated affiliates	6,599	7,044
Other joint ventures
Schedule of Equity Method Investments [Line Items]
Equity income	162	136	$ 182
Equity in net assets of nonconsolidated affiliates	$ 1,807	$ 1,518
SGM
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50.00%	50.00%
SGM | SAIC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50.00%
PATAC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50.00%	50.00%
SGMS
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	49.00%	49.00%
SGMW
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	44.00%	44.00%
Shanghai OnStar
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	40.00%	40.00%
Shanghai OnStar | SGM
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	20.00%
SGM Norsom
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	25.00%	25.00%
SGM Norsom | SGM
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50.00%
SGM Norsom | SAIC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	25.00%
SGM DY
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	25.00%	25.00%
SGM DY | SGM
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50.00%
SGM DY | SAIC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	25.00%
SGM DYPT
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	25.00%	25.00%
SGM DYPT | SGM
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50.00%
SGM DYPT | SAIC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	25.00%
SAIC-GMAC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	35.00%	35.00%
SAIC-GMAC | SGM
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	20.00%
SAIC-GMAC | Shanghai Automotive Group Finance Company Ltd.
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	45.00%
SAIC-GMF Leasing Co., Ltd.
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	35.00%	35.00%
SAIC-GMF Leasing Co., Ltd. | SGM
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	20.00%
SAIC-GMF Leasing Co., Ltd. | SAIC Financial Holdings Company
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	45.00%

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