Investments - Available for sale fixed maturities (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	$ 10,734	$ 10,752
Fixed maturities, available for sale, allowance for expected credit losses	11	12	$ 16	$ 11
Available for sale (AFS) fixed maturities	10,371	10,377
Total fixed maturities
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	10,734	10,752
Fixed maturities, available for sale, allowance for expected credit losses	11	12
Fixed maturities, available for sale, gross unrealized, gains	96	107
Fixed maturities, available for sale, gross unrealized, losses	(448)	(470)
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax	(352)	(363)
Available for sale (AFS) fixed maturities	10,371	10,377
U.S. government and government agencies
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	206	243
Fixed maturities, available for sale, allowance for expected credit losses	0	0
Fixed maturities, available for sale, gross unrealized, gains	0	1
Fixed maturities, available for sale, gross unrealized, losses	(7)	(8)
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax	(7)	(7)
Available for sale (AFS) fixed maturities	199	236
States, municipalities and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	949	1,014
Fixed maturities, available for sale, allowance for expected credit losses	0	0
Fixed maturities, available for sale, gross unrealized, gains	6	8
Fixed maturities, available for sale, gross unrealized, losses	(45)	(38)
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax	(39)	(30)
Available for sale (AFS) fixed maturities	910	984
Foreign government
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	240	236
Fixed maturities, available for sale, allowance for expected credit losses	0	0
Fixed maturities, available for sale, gross unrealized, gains	0	1
Fixed maturities, available for sale, gross unrealized, losses	(5)	(7)
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax	(5)	(6)
Available for sale (AFS) fixed maturities	235	230
Residential MBS
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	1,807	1,788
Fixed maturities, available for sale, allowance for expected credit losses	2	1
Fixed maturities, available for sale, gross unrealized, gains	25	26
Fixed maturities, available for sale, gross unrealized, losses	(156)	(155)
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax	(131)	(129)
Available for sale (AFS) fixed maturities	1,674	1,658
Commercial MBS
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	72	75
Fixed maturities, available for sale, allowance for expected credit losses	0	0
Fixed maturities, available for sale, gross unrealized, gains	0	0
Fixed maturities, available for sale, gross unrealized, losses	0	(1)
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax	0	(1)
Available for sale (AFS) fixed maturities	72	74
Collateralized loan obligations
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	1,605	1,709
Fixed maturities, available for sale, allowance for expected credit losses	3	3
Fixed maturities, available for sale, gross unrealized, gains	13	9
Fixed maturities, available for sale, gross unrealized, losses	(22)	(28)
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax	(9)	(19)
Available for sale (AFS) fixed maturities	1,593	1,687
Other asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	2,469	2,477
Fixed maturities, available for sale, allowance for expected credit losses	6	5
Fixed maturities, available for sale, gross unrealized, gains	13	10
Fixed maturities, available for sale, gross unrealized, losses	(102)	(120)
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax	(89)	(110)
Available for sale (AFS) fixed maturities	2,374	2,362
Corporate and other
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available for sale, amortized cost	3,386	3,210
Fixed maturities, available for sale, allowance for expected credit losses	0	3	$ 5	$ 1
Fixed maturities, available for sale, gross unrealized, gains	39	52
Fixed maturities, available for sale, gross unrealized, losses	(111)	(113)
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax	(72)	(61)
Available for sale (AFS) fixed maturities	$ 3,314	$ 3,146

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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