Other Liabilities and Deferred Revenue (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Other Liabilities [Abstract]
Dealer and Dealers' Customer Allowances and Claims	$ 11,697	$ 10,902
Deferred Revenue, Current	2,854	2,107
Deferred Compensation Liability, Current	1,400	1,661
Interest Payable, Current	1,003	1,057
Other Postretirement Defined Benefit Plan Liabilities Current	345	348
Liability, Defined Benefit Pension Plan, Current	223	229
Other Sundry Liabilities, Current	3,712	3,393
Other Liabilities, Current	21,234	19,697
Pension (a)	9,450	9,932
OPEB (a)	5,684	5,821
Dealer and dealers’ customer allowances and claims	2,189	2,471
Deferred revenue	3,937	3,829
Employee benefit plans	1,155	1,139
Other	1,692	1,519
Total non-current other liabilities and deferred revenue	24,107	24,711
Net pension assets	$ 3,900	$ 3,500