Other Liabilities and Deferred Revenue (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Other Liabilities, Current [Abstract]
Dealer and dealers’ customer allowances and claims	$ 12,702	$ 13,113
Deferred revenue	2,161	2,091
Employee benefit plans	1,752	1,857
Accrued interest	1,215	1,128
OPEB	339	332
Pension	193	185
Other	4,960	3,914
Total current other liabilities and deferred revenue	23,645	22,987
Other Liabilities, Noncurrent [Abstract]
Pension	10,738	9,878
OPEB	6,236	5,740
Dealer and dealers’ customer allowances and claims	3,072	1,921
Deferred revenue	4,559	4,191
Employee benefit plans	1,074	1,104
Other	1,709	1,443
Total non-current other liabilities and deferred revenue	28,379	25,324
Other Current Liabilities
Other Liabilities, Current [Abstract]
Operating lease liabilities	323	367
Other Noncurrent Liabilities
Other Liabilities, Noncurrent [Abstract]
Operating lease liabilities	$ 991	$ 1,047