INVESTMENTS - Fair Value and Gross Unrealized Losses for Securities That Have Been in Continuous Unrealized Loss Position (Detail) - Fixed maturity securities - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	$ 26,342	$ 31,709
Total Unrealized Losses	2,806	4,528
Less than 12 months Fair Value	6,137	20,347
Less than 12 months Unrealized Losses	379	2,213
12 months or Longer Fair Value	20,205	11,362
12 months or Longer Unrealized Losses	2,427	2,315
Dollar-denominated | U.S. government and agencies
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	179	159
Total Unrealized Losses	7	8
Less than 12 months Fair Value	97	85
Less than 12 months Unrealized Losses	3	3
12 months or Longer Fair Value	82	74
12 months or Longer Unrealized Losses	4	5
Dollar-denominated | Municipalities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	700	854
Total Unrealized Losses	51	89
Less than 12 months Fair Value	96	735
Less than 12 months Unrealized Losses	6	57
12 months or Longer Fair Value	604	119
12 months or Longer Unrealized Losses	45	32
Dollar-denominated | Mortgage- and asset-backed securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	1,057	936
Total Unrealized Losses	70	84
Less than 12 months Fair Value	753	640
Less than 12 months Unrealized Losses	55	42
12 months or Longer Fair Value	304	296
12 months or Longer Unrealized Losses	15	42
Dollar-denominated | Public utilities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	1,296	1,852
Total Unrealized Losses	143	180
Less than 12 months Fair Value	690	1,667
Less than 12 months Unrealized Losses	58	144
12 months or Longer Fair Value	606	185
12 months or Longer Unrealized Losses	85	36
Dollar-denominated | Sovereign and supranational
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	33	30
Total Unrealized Losses	10	12
Less than 12 months Fair Value	0	0
Less than 12 months Unrealized Losses	0	0
12 months or Longer Fair Value	33	30
12 months or Longer Unrealized Losses	10	12
Dollar-denominated | Banks/financial institutions
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	857	1,147
Total Unrealized Losses	70	105
Less than 12 months Fair Value	387	786
Less than 12 months Unrealized Losses	13	58
12 months or Longer Fair Value	470	361
12 months or Longer Unrealized Losses	57	47
Dollar-denominated | Other corporate
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	7,385	10,529
Total Unrealized Losses	795	1,201
Less than 12 months Fair Value	2,691	8,636
Less than 12 months Unrealized Losses	118	785
12 months or Longer Fair Value	4,694	1,893
12 months or Longer Unrealized Losses	677	416
Yen-denominated | Japan government and agencies
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	8,274	8,856
Total Unrealized Losses	975	1,724
Less than 12 months Fair Value	529	3,733
Less than 12 months Unrealized Losses	102	580
12 months or Longer Fair Value	7,745	5,123
12 months or Longer Unrealized Losses	873	1,144
Yen-denominated | Municipalities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	283	286
Total Unrealized Losses	35	61
Less than 12 months Fair Value	0	150
Less than 12 months Unrealized Losses	0	26
12 months or Longer Fair Value	283	136
12 months or Longer Unrealized Losses	35	35
Yen-denominated | Mortgage- and asset-backed securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	61	62
Total Unrealized Losses	6	12
Less than 12 months Fair Value	0	38
Less than 12 months Unrealized Losses	0	6
12 months or Longer Fair Value	61	24
12 months or Longer Unrealized Losses	6	6
Yen-denominated | Public utilities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	710	880
Total Unrealized Losses	51	108
Less than 12 months Fair Value	57	576
Less than 12 months Unrealized Losses	2	61
12 months or Longer Fair Value	653	304
12 months or Longer Unrealized Losses	49	47
Yen-denominated | Sovereign and supranational
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	63	71
Total Unrealized Losses	4	5
Less than 12 months Fair Value	0	34
Less than 12 months Unrealized Losses	0	4
12 months or Longer Fair Value	63	37
12 months or Longer Unrealized Losses	4	1
Yen-denominated | Banks/financial institutions
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	3,626	3,957
Total Unrealized Losses	309	531
Less than 12 months Fair Value	425	1,760
Less than 12 months Unrealized Losses	9	174
12 months or Longer Fair Value	3,201	2,197
12 months or Longer Unrealized Losses	300	357
Yen-denominated | Other corporate
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	1,818	2,090
Total Unrealized Losses	280	408
Less than 12 months Fair Value	412	1,507
Less than 12 months Unrealized Losses	13	273
12 months or Longer Fair Value	1,406	583
12 months or Longer Unrealized Losses	$ 267	$ 135