Non-Insurance Revenues from Contracts with Customers (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred non-insurance warranty revenue	$ 4,503	$ 4,023
Contract with customer, liability, revenue recognized	1,200	1,100
Deferred non-insurance warranty acquisition expense	3,476	3,068
Amortization of deferred sales commissions	1,100	900
Capitalized Commission Costs
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred non-insurance warranty acquisition expense	3,500	3,100
Capitalized Administrator Service Costs
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred non-insurance warranty acquisition expense	$ 47	$ 37