INVESTMENTS - Fair Value and Gross Unrealized Losses for Securities That Have Been in Continuous Unrealized Loss Position (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	$ 22,413	$ 14,279
Total Unrealized Losses	2,013	834
Less Than 12 months Fair Value	16,529	2,751
Less Than 12 months Unrealized Losses	1,040	83
12 months or longer Fair Value	5,884	11,528
12 months or longer Unrealized Losses	973	751
Fixed maturities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	21,571	13,496
Total Unrealized Losses	1,915	742
Less Than 12 months Fair Value	16,122	2,557
Less Than 12 months Unrealized Losses	1,024	78
12 months or longer Fair Value	5,449	10,939
12 months or longer Unrealized Losses	891	664
Perpetual securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	651	783
Total Unrealized Losses	94	92
Less Than 12 months Fair Value	216	194
Less Than 12 months Unrealized Losses	12	5
12 months or longer Fair Value	435	589
12 months or longer Unrealized Losses	82	87
Equity securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	191
Total Unrealized Losses	4
Less Than 12 months Fair Value	191
Less Than 12 months Unrealized Losses	4
12 months or longer Fair Value	0
12 months or longer Unrealized Losses	0
Dollar-denominated | Fixed maturities | Municipalities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	80	75
Total Unrealized Losses	6	2
Less Than 12 months Fair Value	80	53
Less Than 12 months Unrealized Losses	6	1
12 months or longer Fair Value	0	22
12 months or longer Unrealized Losses	0	1
Dollar-denominated | Fixed maturities | Public utilities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	2,127	1,001
Total Unrealized Losses	221	36
Less Than 12 months Fair Value	1,689	164
Less Than 12 months Unrealized Losses	132	7
12 months or longer Fair Value	438	837
12 months or longer Unrealized Losses	89	29
Dollar-denominated | Fixed maturities | Banks/financial institutions
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	366	205
Total Unrealized Losses	21	8
Less Than 12 months Fair Value	348	53
Less Than 12 months Unrealized Losses	11	5
12 months or longer Fair Value	18	152
12 months or longer Unrealized Losses	10	3
Dollar-denominated | Fixed maturities | Other corporate
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	13,430	8,072
Total Unrealized Losses	1,302	330
Less Than 12 months Fair Value	11,068	1,901
Less Than 12 months Unrealized Losses	770	62
12 months or longer Fair Value	2,362	6,171
12 months or longer Unrealized Losses	532	268
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
Yen-denominated | Fixed maturities | Public utilities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	1,487	805
Total Unrealized Losses	104	25
Less Than 12 months Fair Value	1,062	98
Less Than 12 months Unrealized Losses	73	1
12 months or longer Fair Value	425	707
12 months or longer Unrealized Losses	31	24
Yen-denominated | Fixed maturities | Sovereign and supranational
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	580	359
Total Unrealized Losses	26	14
Less Than 12 months Fair Value	385	0
Less Than 12 months Unrealized Losses	13	0
12 months or longer Fair Value	195	359
12 months or longer Unrealized Losses	13	14
Yen-denominated | Fixed maturities | Banks/financial institutions
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	2,350	1,828
Total Unrealized Losses	158	267
Less Than 12 months Fair Value	1,147	166
Less Than 12 months Unrealized Losses	14	0
12 months or longer Fair Value	1,203	1,662
12 months or longer Unrealized Losses	144	267
Yen-denominated | Fixed maturities | Other corporate
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	1,151	1,151
Total Unrealized Losses	77	60
Less Than 12 months Fair Value	343	122
Less Than 12 months Unrealized Losses	5	2
12 months or longer Fair Value	808	1,029
12 months or longer Unrealized Losses	72	58
Yen-denominated | Perpetual securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	645	783
Total Unrealized Losses	93	92
Less Than 12 months Fair Value	216	194
Less Than 12 months Unrealized Losses	12	5
12 months or longer Fair Value	429	589
12 months or longer Unrealized Losses	81	$ 87
Yen-denominated | Equity securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	191
Total Unrealized Losses	4
Less Than 12 months Fair Value	191
Less Than 12 months Unrealized Losses	4
12 months or longer Fair Value	0
12 months or longer Unrealized Losses	$ 0