INVESTMENTS - Fair Value and Gross Unrealized Losses for Securities That Have Been in Continuous Unrealized Loss Position (Details) - Fixed maturity securities - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Investments, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	$ 239	$ 481
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	42	184
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	7,914	10,781
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	2,948	6,902
12 months or longer Unrealized Losses	4,966	3,879
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	197	297
Yen-denominated | Japan government and agencies
Investments, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	61	52
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3	52
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	2,868	2,604
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	445	2,604
12 months or longer Unrealized Losses	2,423	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	58	0
Yen-denominated | Municipalities
Investments, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	5	5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	4
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	187	183
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	53	169
12 months or longer Unrealized Losses	134	14
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5	1
Yen-denominated | Mortgage- and asset-backed securities
Investments, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	1	1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	1
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	33	37
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	37
12 months or longer Unrealized Losses	33	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1	0
Yen-denominated | Public utilities
Investments, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	2	1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	1
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	26	135
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	135
12 months or longer Unrealized Losses	26	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2	0
Yen-denominated | Banks/financial institutions
Investments, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	72	102
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	16	36
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	2,074	1,809
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	1,011	765
12 months or longer Unrealized Losses	1,063	1,044
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	56	66
Yen-denominated | Other corporate
Investments, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	26	37
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4	13
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	541	613
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	274	290
12 months or longer Unrealized Losses	267	323
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	22	24
Dollar-denominated | U.S. government and agencies
Investments, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0
12 months or longer Unrealized Losses	1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Dollar-denominated | Municipalities
Investments, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	2	2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2	2
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	82	94
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	79	94
12 months or longer Unrealized Losses	3	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Dollar-denominated | Mortgage- and asset-backed securities
Investments, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	2	5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2	5
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	278	360
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	278	360
12 months or longer Unrealized Losses	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Dollar-denominated | Public utilities
Investments, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	5	15
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2	7
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	130	326
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	70	208
12 months or longer Unrealized Losses	60	118
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3	8
Dollar-denominated | Sovereign and supranational
Investments, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	6	3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1	3
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	37	39
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	6	39
12 months or longer Unrealized Losses	31	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5	0
Dollar-denominated | Banks/financial institutions
Investments, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	3	7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3	1
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	292	82
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	274	44
12 months or longer Unrealized Losses	18	38
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	6
Dollar-denominated | Other corporate
Investments, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss, Total	53	251
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	8	59
Debt Securities, Available-for-sale, Unrealized Loss Position, Total	1,365	4,499
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	458	2,157
12 months or longer Unrealized Losses	907	2,342
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 45	$ 192