INVESTMENTS - Fair Value and Gross Unrealized Losses for Securities That Have Been in Continuous Unrealized Loss Position (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	$ 15,091	$ 22,413
Total Unrealized Losses	1,420	2,013
Less than 12 months Fair Value	5,492	16,529
Less than 12 months Unrealized Losses	443	1,040
12 months or longer Fair Value	9,599	5,884
12 months or longer Unrealized Losses	977	973
Fixed maturities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	13,423	21,571
Total Unrealized Losses	1,127	1,915
Less than 12 months Fair Value	4,313	16,122
Less than 12 months Unrealized Losses	307	1,024
12 months or longer Fair Value	9,110	5,449
12 months or longer Unrealized Losses	820	891
Perpetual securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	989	651
Total Unrealized Losses	199	94
Less than 12 months Fair Value	500	216
Less than 12 months Unrealized Losses	42	12
12 months or longer Fair Value	489	435
12 months or longer Unrealized Losses	157	82
Equity securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	679	191
Total Unrealized Losses	94	4
Less than 12 months Fair Value	679	191
Less than 12 months Unrealized Losses	94	4
12 months or longer Fair Value	0	0
12 months or longer Unrealized Losses	0	0
Dollar-denominated | Fixed maturities | Municipalities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	46	80
Total Unrealized Losses	7	6
Less than 12 months Fair Value	0	80
Less than 12 months Unrealized Losses	0	6
12 months or longer Fair Value	46	0
12 months or longer Unrealized Losses	7	0
Dollar-denominated | Fixed maturities | Public utilities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	1,216	2,127
Total Unrealized Losses	76	221
Less than 12 months Fair Value	283	1,689
Less than 12 months Unrealized Losses	12	132
12 months or longer Fair Value	933	438
12 months or longer Unrealized Losses	64	89
Dollar-denominated | Fixed maturities | Banks/financial institutions
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	148	366
Total Unrealized Losses	16	21
Less than 12 months Fair Value	78	348
Less than 12 months Unrealized Losses	6	11
12 months or longer Fair Value	70	18
12 months or longer Unrealized Losses	10	10
Dollar-denominated | Fixed maturities | Other corporate
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	8,556	13,430
Total Unrealized Losses	784	1,302
Less than 12 months Fair Value	3,203	11,068
Less than 12 months Unrealized Losses	255	770
12 months or longer Fair Value	5,353	2,362
12 months or longer Unrealized Losses	529	532
Dollar-denominated | Perpetual securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value		6
Total Unrealized Losses		1
Less than 12 months Fair Value		0
Less than 12 months Unrealized Losses		0
12 months or longer Fair Value		6
12 months or longer Unrealized Losses		1
Dollar-denominated | Equity securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	268
Total Unrealized Losses	18
Less than 12 months Fair Value	268
Less than 12 months Unrealized Losses	18
12 months or longer Fair Value	0
12 months or longer Unrealized Losses	0
Yen-denominated | Fixed maturities | Public utilities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	823	1,487
Total Unrealized Losses	23	104
Less than 12 months Fair Value	182	1,062
Less than 12 months Unrealized Losses	13	73
12 months or longer Fair Value	641	425
12 months or longer Unrealized Losses	10	31
Yen-denominated | Fixed maturities | Sovereign and supranational
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	236	580
Total Unrealized Losses	7	26
Less than 12 months Fair Value	0	385
Less than 12 months Unrealized Losses	0	13
12 months or longer Fair Value	236	195
12 months or longer Unrealized Losses	7	13
Yen-denominated | Fixed maturities | Banks/financial institutions
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	1,428	2,350
Total Unrealized Losses	151	158
Less than 12 months Fair Value	240	1,147
Less than 12 months Unrealized Losses	3	14
12 months or longer Fair Value	1,188	1,203
12 months or longer Unrealized Losses	148	144
Yen-denominated | Fixed maturities | Other corporate
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	970	1,151
Total Unrealized Losses	63	77
Less than 12 months Fair Value	327	343
Less than 12 months Unrealized Losses	18	5
12 months or longer Fair Value	643	808
12 months or longer Unrealized Losses	45	72
Yen-denominated | Perpetual securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	989	645
Total Unrealized Losses	199	93
Less than 12 months Fair Value	500	216
Less than 12 months Unrealized Losses	42	12
12 months or longer Fair Value	489	429
12 months or longer Unrealized Losses	157	81
Yen-denominated | Equity securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	411	191
Total Unrealized Losses	76	4
Less than 12 months Fair Value	411	191
Less than 12 months Unrealized Losses	76	4
12 months or longer Fair Value	0	0
12 months or longer Unrealized Losses	$ 0	$ 0