Goodwill and Intangible Assets Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 6,001	$ 13,704
Accumulated Amortization	2,283	9,712
Net Carrying Amount	3,718	3,992
Amortization expense	247	278	$ 325
Estimated amortization expense, 2019	184
Estimated amortization expense, 2020	184
Estimated amortization expense, 2021	184
Estimated amortization expense, 2022	184
Estimated amortization expense, 2023	184
Removal of fully amortized intangible assets	7,700
Technology and Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	734	8,092
Accumulated Amortization	457	7,735
Net Carrying Amount	277	357
Brands [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	4,299	4,302
Accumulated Amortization	1,165	1,044
Net Carrying Amount	3,134	3,258
Dealer network, customer relationships and other [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	968	1,310
Accumulated Amortization	661	933
Net Carrying Amount	$ 307	$ 377