Deferred Policy Acquisition Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Long-duration contracts
Beginning balance	$ 5,773
Deferred policy acquisition costs	5,787	$ 5,946
Ending balance	5,787	5,946
Allstate Health and Benefits
Long-duration contracts
Beginning balance	64	540
Acquisition costs deferred	48	48
Amortization charged to income	(33)	(31)
Experience adjustment	(4)	(11)
Classified as held for sale	(5)
Deferred policy acquisition costs	70	546
Ending balance	70	546
Accident and health insurance long-duration contracts
Long-duration contracts
Beginning balance	55	321
Acquisition costs deferred	29	26
Amortization charged to income	(21)	(20)
Experience adjustment	(4)	(10)
Classified as held for sale	2
Deferred policy acquisition costs	61	317
Ending balance	61	317
Other health and benefit contracts
Long-duration contracts
Beginning balance	9	219
Acquisition costs deferred	19	22
Amortization charged to income	(12)	(11)
Experience adjustment	0	(1)
Classified as held for sale	(7)
Deferred policy acquisition costs	9	229
Ending balance	9	229
Allstate Protection
Long-duration contracts
Deferred policy acquisition costs	2,565	2,374
Ending balance	2,565	2,374
Protection Services
Long-duration contracts
Deferred policy acquisition costs	3,152	3,026
Ending balance	$ 3,152	$ 3,026