Deferred Policy Acquisition Costs (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Long-duration contracts
Beginning balance	$ 5,940
Deferred policy acquisition costs	5,751	$ 5,824
Ending balance	5,751	5,824
Allstate Health and Benefits
Long-duration contracts
Beginning balance	511	502
Acquisition costs deferred	129	109
Amortization charged to income	(86)	(82)
Experience adjustment	(16)	(25)
Reclassified to assets held for sale	(489)
Deferred policy acquisition costs	49	504
Short-duration contracts	6	27
Ending balance	49	504
Accident and health insurance
Long-duration contracts
Beginning balance	321	322
Acquisition costs deferred	76	73
Amortization charged to income	(59)	(54)
Experience adjustment	(15)	(22)
Reclassified to assets held for sale	(277)
Deferred policy acquisition costs	46	319
Ending balance	46	319
Traditional life
Long-duration contracts
Beginning balance	90	79
Acquisition costs deferred	41	24
Amortization charged to income	(16)	(17)
Experience adjustment	(1)	(1)
Reclassified to assets held for sale	(111)
Deferred policy acquisition costs	3	85
Ending balance	3	85
Interest-sensitive life insurance
Long-duration contracts
Beginning balance	100	101
Acquisition costs deferred	12	12
Amortization charged to income	(11)	(11)
Experience adjustment	0	(2)
Reclassified to assets held for sale	(101)
Deferred policy acquisition costs	0	100
Ending balance	0	100
Allstate Protection
Long-duration contracts
Deferred policy acquisition costs	2,590	2,358
Ending balance	2,590	2,358
Protection Services
Long-duration contracts
Deferred policy acquisition costs	3,106	2,935
Ending balance	$ 3,106	$ 2,935