INVESTMENTS - Held-to-Maturity Debt Securities (Details) - USD ($) $ in Millions	Sep. 30, 2023		Dec. 31, 2022
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 16,904		$ 19,063
Allowance for Credit Loss	5		7
Total fixed maturity securities, held-to- maturity, amortized cost	16,899	[1]	19,056
Gross Unrealized Gains	1,561		2,154
Gross Unrealized Losses	0		0
Fair   Value	18,460		21,210
Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	16,904		19,063
Allowance for Credit Loss	5		7
Total fixed maturity securities, held-to- maturity, amortized cost	16,899		19,056
Gross Unrealized Gains	1,561		2,154
Gross Unrealized Losses	0		0
Fair   Value	18,460		21,210
Japan government and agencies | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	16,202		18,269
Allowance for Credit Loss	2		2
Total fixed maturity securities, held-to- maturity, amortized cost	16,200		18,267
Gross Unrealized Gains	1,487		2,045
Gross Unrealized Losses	0		0
Fair   Value	17,687		20,312
Municipalities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	253		287
Fair   Value	289		335
Municipalities | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	253		287
Allowance for Credit Loss	0		0
Total fixed maturity securities, held-to- maturity, amortized cost	253		287
Gross Unrealized Gains	36		48
Gross Unrealized Losses	0		0
Fair   Value	289		335
Public utilities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	33		37
Fair   Value	36		41
Public utilities | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	33		38
Allowance for Credit Loss	0		1
Total fixed maturity securities, held-to- maturity, amortized cost	33		37
Gross Unrealized Gains	3		4
Gross Unrealized Losses	0		0
Fair   Value	36		41
Sovereign and supranational
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	396		446
Fair   Value	429		500
Sovereign and supranational | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	399		450
Allowance for Credit Loss	3		4
Total fixed maturity securities, held-to- maturity, amortized cost	396		446
Gross Unrealized Gains	33		54
Gross Unrealized Losses	0		0
Fair   Value	429		500
Other corporate
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	17		19
Fair   Value	19		22
Other corporate | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	17		19
Allowance for Credit Loss	0		0
Total fixed maturity securities, held-to- maturity, amortized cost	17		19
Gross Unrealized Gains	2		3
Gross Unrealized Losses	0		0
Fair   Value	$ 19		$ 22

[1] Net of allowance for credit losses