Summary of Significant Accounting Policies, Accounting Changes (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Changes [Abstract]
Shareholders' equity	$ 19,175	$ 19,181		$ 21,930	$ 21,386
Allowance for Credit Losses	18	40		0
Other assets	3,344	3,069
Other liabilities	4,529	4,623
Deferred non-insurance warranty acquisition expenses	3,476	3,068
Deferred non-insurance warranty revenue	4,503	4,023
Retained Earnings
Accounting Changes [Abstract]
Shareholders' equity	$ 14,776	$ 14,150		15,823	$ 15,773
Cumulative Effect, Period of Adoption, Adjustment
Accounting Changes [Abstract]
Shareholders' equity				(5)
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings
Accounting Changes [Abstract]
Shareholders' equity				$ (5)
ASC 326
Accounting Changes [Abstract]
Allowance for Credit Losses			$ 6
ASC 326 | Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings
Accounting Changes [Abstract]
Shareholders' equity			$ (5)