INVESTMENTS - Held-to-Maturity Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2023		Dec. 31, 2022
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity, fixed maturity securities, amortized cost	$ 18,942		$ 19,063
Allowance for Credit Loss	6		7
Total fixed maturity securities, held to maturity, amortized cost	18,936	[1]	19,056
Gross Unrealized Gains	2,680		2,154
Gross Unrealized Losses	0		0
Fair Value	21,616		21,210
Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity, fixed maturity securities, amortized cost	18,942		19,063
Allowance for Credit Loss	6		7
Total fixed maturity securities, held to maturity, amortized cost	18,936		19,056
Gross Unrealized Gains	2,680		2,154
Gross Unrealized Losses	0		0
Fair Value	21,616		21,210
Japan government and agencies | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity, fixed maturity securities, amortized cost	18,154		18,269
Allowance for Credit Loss	2		2
Total fixed maturity securities, held to maturity, amortized cost	18,152		18,267
Gross Unrealized Gains	2,548		2,045
Gross Unrealized Losses	0		0
Fair Value	20,700		20,312
Municipalities
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity, fixed maturity securities, amortized cost	285		287
Fair Value	341		335
Municipalities | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity, fixed maturity securities, amortized cost	285		287
Allowance for Credit Loss	0		0
Total fixed maturity securities, held to maturity, amortized cost	285		287
Gross Unrealized Gains	56		48
Gross Unrealized Losses	0		0
Fair Value	341		335
Public utilities
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity, fixed maturity securities, amortized cost	37		37
Fair Value	42		41
Public utilities | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity, fixed maturity securities, amortized cost	37		38
Allowance for Credit Loss	0		1
Total fixed maturity securities, held to maturity, amortized cost	37		37
Gross Unrealized Gains	5		4
Gross Unrealized Losses	0		0
Fair Value	42		41
Sovereign and supranational
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity, fixed maturity securities, amortized cost	443		446
Fair Value	510		500
Sovereign and supranational | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity, fixed maturity securities, amortized cost	447		450
Allowance for Credit Loss	4		4
Total fixed maturity securities, held to maturity, amortized cost	443		446
Gross Unrealized Gains	67		54
Gross Unrealized Losses	0		0
Fair Value	510		500
Other corporate
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity, fixed maturity securities, amortized cost	19		19
Fair Value	23		22
Other corporate | Yen-denominated
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity, fixed maturity securities, amortized cost	19		19
Allowance for Credit Loss	0		0
Total fixed maturity securities, held to maturity, amortized cost	19		19
Gross Unrealized Gains	4		3
Gross Unrealized Losses	0		0
Fair Value	$ 23		$ 22

[1] Net of allowance for credit losses