Reserve for Property and Casualty Insurance Claims and Claims Expense - Reconciliation of total claims and claims expense incurred and paid by coverage (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Increase (decrease) in claims and claims expense
Incurred	$ 37,264	$ 29,318	$ 22,001
Property and casualty
Increase (decrease) in claims and claims expense
Incurred	37,264
Paid	(32,480)	$ (28,245)	$ (22,224)
Property and casualty | Claims incurred and paid from before 2018
Increase (decrease) in claims and claims expense
Incurred	80
Paid	(787)
Auto insurance - liability coverage | Property and casualty
Increase (decrease) in claims and claims expense
Incurred	14,376
Paid	(11,173)
Auto insurance - physical damage coverage | Property and casualty
Increase (decrease) in claims and claims expense
Incurred	9,411
Paid	(8,802)
Homeowners insurance | Property and casualty
Increase (decrease) in claims and claims expense
Incurred	6,971
Paid	(5,977)
Total auto and homeowners insurance | Property and casualty
Increase (decrease) in claims and claims expense
Incurred	30,758
Paid	(25,952)
Other personal lines | Property and casualty
Increase (decrease) in claims and claims expense
Incurred	1,520
Paid	(1,317)
Commercial lines | Property and casualty
Increase (decrease) in claims and claims expense
Incurred	1,256
Paid	(817)
Protection Services | Property and casualty
Increase (decrease) in claims and claims expense
Incurred	440
Paid	(438)
Run-off Property-Liability | Property and casualty
Increase (decrease) in claims and claims expense
Incurred	116
Paid	(86)
Unallocated loss adjustment expenses (“ULAE”) | Property and casualty
Increase (decrease) in claims and claims expense
Incurred	3,048
Paid	(2,847)
Other | Property and casualty
Increase (decrease) in claims and claims expense
Incurred	46
Paid	$ (236)