Reinsurance - Summary of the Composition of Pool of Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Effects of Reinsurance [Line Items]
Fixed maturity securities - available for sale	$ 70,528		$ 71,032
Fixed maturity securities - fair value option	677		741
Short-term investments	8,196		11,141
Other	4,683		4,773
Total assets	161,543		161,254
Carrying Value
Effects of Reinsurance [Line Items]
Short-term investments	3,319		5,232
Other	17		16
Commercial mortgage and other loans
Effects of Reinsurance [Line Items]
Loans, carrying value	2,409		2,495
Fortitude Holdings
Effects of Reinsurance [Line Items]
Change in net unrealized gains (losses), gross	(17)	$ 85
Change in net unrealized gains (losses), net of tax	(13)	$ 67
Derivative asset, Fair value of collateral	2		1
Derivative liability, Fair value of collateral	27		31
Fortitude Holdings | Carrying Value
Effects of Reinsurance [Line Items]
Fixed maturity securities - available for sale	1,697		1,780
Fixed maturity securities - fair value option	670		734
Short-term investments	155		43
Funds withheld investment assets	2,867		2,916
Derivative assets, net	1		0
Other	101		137
Total assets	2,969		3,053
Fortitude Holdings | Estimated Fair Value
Effects of Reinsurance [Line Items]
Fixed maturity securities - available for sale	1,697		1,780
Fixed maturity securities - fair value option	670		734
Short-term investments	155		43
Funds withheld investment assets	2,858		2,901
Derivative assets, net	1		0
Other, fair value	101		137
Total	2,960		3,038
Fortitude Holdings | Commercial mortgage and other loans | Carrying Value
Effects of Reinsurance [Line Items]
Loans, carrying value	345		359
Fortitude Holdings | Commercial mortgage and other loans | Estimated Fair Value
Effects of Reinsurance [Line Items]
Loans, fair value	$ 336		$ 344