INVESTMENTS - Held-to-Maturity Debt Securities (Detail) - USD ($) $ in Millions	Dec. 31, 2025		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 16,125		$ 15,971
Allowance for Credit Losses	5		5	$ 5	$ 7
Total fixed maturity securities, held-to-maturity, amortized cost	16,120	[1]	15,966
Gross Unrealized Gains	87		815
Gross Unrealized Losses	731		9
Fair Value	15,476		16,772
Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	16,125		15,971
Allowance for Credit Losses	5		5
Total fixed maturity securities, held-to-maturity, amortized cost	16,120		15,966
Gross Unrealized Gains	87		815
Gross Unrealized Losses	731		9
Fair Value	15,476		16,772
Japan government and agencies | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	15,461		15,311
Allowance for Credit Losses	2		2
Total fixed maturity securities, held-to-maturity, amortized cost	15,459		15,309
Gross Unrealized Gains	81		759
Gross Unrealized Losses	713		9
Fair Value	14,827		16,059
Municipalities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	235		235
Fair Value	229		257
Municipalities | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	235		235
Allowance for Credit Losses	0		0
Total fixed maturity securities, held-to-maturity, amortized cost	235		235
Gross Unrealized Gains	0		22
Gross Unrealized Losses	6		0
Fair Value	229		257
Public utilities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	32		32
Fair Value	29		33
Public utilities | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	32		32
Allowance for Credit Losses	0		0
Total fixed maturity securities, held-to-maturity, amortized cost	32		32
Gross Unrealized Gains	0		1
Gross Unrealized Losses	3		0
Fair Value	29		33
Sovereign and supranational
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	378		374
Fair Value	375		405
Sovereign and supranational | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	381		377
Allowance for Credit Losses	3		3
Total fixed maturity securities, held-to-maturity, amortized cost	378		374
Gross Unrealized Gains	6		31
Gross Unrealized Losses	9		0
Fair Value	375		405
Other corporate
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	16		16
Fair Value	16		18
Other corporate | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	16		16
Allowance for Credit Losses	0		0
Total fixed maturity securities, held-to-maturity, amortized cost	16		16
Gross Unrealized Gains	0		2
Gross Unrealized Losses	0		0
Fair Value	$ 16		$ 18

[1] Net of allowance for credit losses