Deferred Policy Acquisition Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Movement Analysis of Deferred Policy Acquisition Costs and Present Value of Future Profits [Roll Forward]
Beginning balance	$ 5,940	$ 5,442	$ 4,738
Acquisition costs deferred	8,393	7,776	7,338
Amortization charged to income	(8,022)	(7,246)	(6,604)
Experience adjustment	(17)	(32)	(30)
Reclassified to assets held for sale	(521)
Ending balance	5,773	5,940	5,442
Accident and health insurance long-duration contracts
Movement Analysis of Deferred Policy Acquisition Costs and Present Value of Future Profits [Roll Forward]
Beginning balance	321	322	339
Acquisition costs deferred	104	100	88
Amortization charged to income	(81)	(73)	(77)
Experience adjustment	(16)	(28)	(28)
Reclassified to assets held for sale	(273)
Ending balance	55	321	322
Other health and benefit contracts
Movement Analysis of Deferred Policy Acquisition Costs and Present Value of Future Profits [Roll Forward]
Beginning balance	219	206	154
Acquisition costs deferred	87	62	83
Amortization charged to income	(48)	(45)	(29)
Experience adjustment	(1)	(4)	(2)
Reclassified to assets held for sale	(248)
Ending balance	9	219	206
Allstate Protection
Movement Analysis of Deferred Policy Acquisition Costs and Present Value of Future Profits [Roll Forward]
Beginning balance	2,378	2,145	1,951
Acquisition costs deferred	6,846	6,302	5,764
Amortization charged to income	(6,676)	(6,069)	(5,570)
Experience adjustment	0	0	0
Reclassified to assets held for sale	0
Ending balance	2,548	2,378	2,145
Protection Services
Movement Analysis of Deferred Policy Acquisition Costs and Present Value of Future Profits [Roll Forward]
Beginning balance	3,022	2,769	2,294
Acquisition costs deferred	1,356	1,312	1,403
Amortization charged to income	(1,217)	(1,059)	(928)
Experience adjustment	0	0	0
Reclassified to assets held for sale	0
Ending balance	$ 3,161	$ 3,022	$ 2,769