New Accounting Standards Cumulative Effect of Changes due to Adoption (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Financing Receivable, after Allowance for Credit Loss, Current	$ 41,847			$ 53,582	$ 53,651
Accounts Receivable, after Allowance for Credit Loss, Current	10,114			9,234	9,237
Financing Receivable, after Allowance for Credit Loss, Noncurrent	55,659			53,520	53,703
Equity in net assets of affiliated companies	4,741			2,512	2,519
Deferred income taxes				11,865
Deferred income taxes				432
Retained earnings	33,161	$ 30,855	$ 29,698		33,230	$ 35,387	$ 36,136	$ 36,434	$ 35,966
Retained Earnings (Accumulated Deficit)	21,031			20,118	20,320
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 21,031	$ 18,645	$ 17,527		20,320	$ 22,590	$ 22,769	$ 23,226	$ 22,668
Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Financing Receivable, after Allowance for Credit Loss, Current				(69)
Accounts Receivable, after Allowance for Credit Loss, Current				(3)
Financing Receivable, after Allowance for Credit Loss, Noncurrent				(183)
Equity in net assets of affiliated companies				(7)
Deferred income taxes				2
Deferred income taxes				(58)
Retained Earnings (Accumulated Deficit)				$ (202)
Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Financing Receivable, after Allowance for Credit Loss, Current					53,651
Accounts Receivable, after Allowance for Credit Loss, Current					9,237
Financing Receivable, after Allowance for Credit Loss, Noncurrent					53,703
Equity in net assets of affiliated companies					2,519
Deferred income taxes					11,863
Deferred income taxes					490
Retained Earnings (Accumulated Deficit)					$ 20,320