Non-Insurance Revenues from Contracts with Customers (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	[1]
Revenue from Contract with Customer [Abstract]
Deferred non-insurance warranty revenue	$ 4,736		$ 4,736		$ 4,714
Contract with customer, liability, revenue recognized	200	$ 300	900	$ 1,000
Deferred non-insurance warranty acquisition expense	$ 3,688		$ 3,688		$ 3,671

[1] As of January 1, 2023, the Company adopted ASU 2018-12 using the modified retrospective method applied as of the transition date of January 1, 2021. Prior period amounts in the financial statements have been adjusted to reflect application of the new guidance. See Note A to the Condensed Consolidated Financial Statements for additional information.