Marketable and Other Securities - Fair Value of Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	$ 22,148
Total cash and cash equivalents	26,939	$ 19,069
Cash and cash equivalents	248	292
Total restricted cash	2,917	3,874
Due in one year or less	19,357
Due between one and five years	2,791
Total available-for-sale debt securities with contractual maturities	22,148
Cruise [Member]
Marketable Securities [Line Items]
Total cash and cash equivalents	539	2,300
GM Korea [Member]
Marketable Securities [Line Items]
Cash and time deposits	0	248
Cash and cash equivalents [Member]
Marketable Securities [Line Items]
Cash and time deposits	11,542	6,828
Total available-for-sale debt securities with contractual maturities	12,814	9,470
Total available-for-sale debt securities with contractual maturities	12,814	9,470
Cash and cash equivalents [Member] \| Level 1 [Member]
Marketable Securities [Line Items]
Money market funds	2,583	2,771
Marketable debt securities [Member]
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	9,962	4,174
Total available-for-sale debt securities with contractual maturities	9,962	4,174
Marketable debt securities [Member] \| Cruise [Member]
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	1,400	266
Total available-for-sale debt securities with contractual maturities	1,400	266
Other current assets [Member] \| Level 1 [Member]
Marketable Securities [Line Items]
Money market funds	2,669	3,582
U.S. government and agencies [Member] \| Cash and cash equivalents [Member] \| Level 2 [Member]
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	4,600	1,484
Total available-for-sale debt securities with contractual maturities	4,600	1,484
U.S. government and agencies [Member] \| Marketable debt securities [Member] \| Level 2 [Member]
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	3,042	226
Total available-for-sale debt securities with contractual maturities	3,042	226
Corporate debt [Member] \| Cash and cash equivalents [Member] \| Level 2 [Member]
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	5,517	5,863
Total available-for-sale debt securities with contractual maturities	5,517	5,863
Corporate debt [Member] \| Marketable debt securities [Member] \| Level 2 [Member]
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	3,798	2,932
Total available-for-sale debt securities with contractual maturities	3,798	2,932
Mortgage and asset-backed [Member] \| Marketable debt securities [Member] \| Level 2 [Member]
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	628	681
Total available-for-sale debt securities with contractual maturities	628	681
Sovereign debt [Member] \| Cash and cash equivalents [Member] \| Level 2 [Member]
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	2,697	2,123
Total available-for-sale debt securities with contractual maturities	2,697	2,123
Sovereign debt [Member] \| Marketable debt securities [Member] \| Level 2 [Member]
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	2,494	335
Total available-for-sale debt securities with contractual maturities	$ 2,494	$ 335

Sum of cash (other than available-for-sale and trading securities) and time deposits.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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