Marketable and Other Securities Fair Value of Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Marketable Securities [Line Items]
Total cash and cash equivalents	$ 17,176	$ 20,844
Total restricted cash	3,605	2,652
Due in one year or less	7,671
Due between one and five years	4,358
Total available-for-sale debt securities with contractual maturities	12,029
GM Cruise [Member]
Marketable Securities [Line Items]
Total cash and cash equivalents	2,100	2,300
GM Korea [Member]
Marketable Securities [Line Items]
Cash and time deposits	504	616
Cash and Cash Equivalents [Member]
Marketable Securities [Line Items]
Cash and time deposits	7,469	7,254
Total available-for-sale debt securities with contractual maturities	6,755	10,423
Cash and Cash Equivalents [Member] \| Level 1 [Member]
Marketable Securities [Line Items]
Money market funds	2,952	3,167
Marketable Debt Securities [Member]
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	6,021	5,966
Restricted cash - cash equivalents [Member]
Marketable Securities [Line Items]
Cash and cash equivalents	237	260
Restricted cash - cash equivalents [Member] \| Level 1 [Member]
Marketable Securities [Line Items]
Money market funds	3,368	2,392
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	3,798	4,656
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	1,231	1,230
Corporate debt [Member] \| Cash and Cash Equivalents [Member] \| Level 2 [Member]
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	2,683	3,791
Corporate debt [Member] \| Marketable Debt Securities [Member] \| Level 2 [Member]
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	3,482	3,478
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	747	695
Sovereign debt [Member] \| Cash and Cash Equivalents [Member] \| Level 2 [Member]
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	274	1,976
Sovereign debt [Member] \| Marketable Debt Securities [Member] \| Level 2 [Member]
Marketable Securities [Line Items]
Total available-for-sale debt securities with contractual maturities	$ 561	$ 563

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

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