INVESTMENTS - Fair Value and Gross Unrealized Losses for Securities That Have Been in Continuous Unrealized Loss Position (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	$ 26,327	$ 36,214
Total Unrealized Losses	2,021	2,746
Less than 12 months Fair Value	13,811	27,790
Less than 12 months Unrealized Losses	568	1,376
12 months or longer Fair Value	12,516	8,424
12 months or longer Unrealized Losses	1,453	1,370
Fixed Maturities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	24,774	34,828
Total Unrealized Losses	1,764	2,519
Less than 12 months Fair Value	13,401	26,985
Less than 12 months Unrealized Losses	560	1,293
12 months or longer Fair Value	11,373	7,843
12 months or longer Unrealized Losses	1,204	1,226
Fixed Maturities | Japan government and agencies | Yen Denominated
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	1,014	8,869
Total Unrealized Losses	3	34
Less than 12 months Fair Value	1,009	8,869
Less than 12 months Unrealized Losses	3	34
12 months or longer Fair Value	5	0
12 months or longer Unrealized Losses	0	0
Fixed Maturities | Municipalities | Dollar Denominated
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	91	177
Total Unrealized Losses	4	12
Less than 12 months Fair Value	70	145
Less than 12 months Unrealized Losses	2	8
12 months or longer Fair Value	21	32
12 months or longer Unrealized Losses	2	4
Fixed Maturities | Public Utilities | Dollar Denominated
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	1,700	2,023
Total Unrealized Losses	102	183
Less than 12 months Fair Value	1,342	1,740
Less than 12 months Unrealized Losses	70	143
12 months or longer Fair Value	358	283
12 months or longer Unrealized Losses	32	40
Fixed Maturities | Public Utilities | Yen Denominated
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	1,959	2,519
Total Unrealized Losses	131	140
Less than 12 months Fair Value	1,119	1,816
Less than 12 months Unrealized Losses	47	54
12 months or longer Fair Value	840	703
12 months or longer Unrealized Losses	84	86
Fixed Maturities | Sovereign and Supranational | Dollar Denominated
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	13	12
Total Unrealized Losses	0	1
Less than 12 months Fair Value	13	12
Less than 12 months Unrealized Losses	0	1
12 months or longer Fair Value	0	0
12 months or longer Unrealized Losses	0	0
Fixed Maturities | Sovereign and Supranational | Yen Denominated
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	887	1,152
Total Unrealized Losses	56	100
Less than 12 months Fair Value	358	791
Less than 12 months Unrealized Losses	2	34
12 months or longer Fair Value	529	361
12 months or longer Unrealized Losses	54	66
Fixed Maturities | Banks/financial Institutions | Dollar Denominated
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	381	547
Total Unrealized Losses	17	33
Less than 12 months Fair Value	283	454
Less than 12 months Unrealized Losses	11	23
12 months or longer Fair Value	98	93
12 months or longer Unrealized Losses	6	10
Fixed Maturities | Banks/financial Institutions | Yen Denominated
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	4,665	4,533
Total Unrealized Losses	513	570
Less than 12 months Fair Value	1,187	2,322
Less than 12 months Unrealized Losses	28	107
12 months or longer Fair Value	3,478	2,211
12 months or longer Unrealized Losses	485	463
Fixed Maturities | Other Corporate | Dollar Denominated
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	11,291	11,588
Total Unrealized Losses	725	1,170
Less than 12 months Fair Value	7,334	8,504
Less than 12 months Unrealized Losses	371	733
12 months or longer Fair Value	3,957	3,084
12 months or longer Unrealized Losses	354	437
Fixed Maturities | Other Corporate | Yen Denominated
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	2,685	3,372
Total Unrealized Losses	211	272
Less than 12 months Fair Value	598	2,296
Less than 12 months Unrealized Losses	24	152
12 months or longer Fair Value	2,087	1,076
12 months or longer Unrealized Losses	187	120
Fixed Maturities | US government and agencies | Dollar Denominated
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	88	36
Total Unrealized Losses	2	4
Less than 12 months Fair Value	88	36
Less than 12 months Unrealized Losses	2	4
12 months or longer Fair Value	0	0
12 months or longer Unrealized Losses	0	0
Perpetual securities:
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	1,548	1,381
Total Unrealized Losses	256	226
Less than 12 months Fair Value	405	800
Less than 12 months Unrealized Losses	8	82
12 months or longer Fair Value	1,143	581
12 months or longer Unrealized Losses	248	144
Perpetual securities: | Dollar Denominated
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	63	59
Total Unrealized Losses	6	9
Less than 12 months Fair Value	56	52
Less than 12 months Unrealized Losses	4	8
12 months or longer Fair Value	7	7
12 months or longer Unrealized Losses	2	1
Perpetual securities: | Yen Denominated
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	1,485	1,322
Total Unrealized Losses	250	217
Less than 12 months Fair Value	349	748
Less than 12 months Unrealized Losses	4	74
12 months or longer Fair Value	1,136	574
12 months or longer Unrealized Losses	246	143
Equity Securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	5	5
Total Unrealized Losses	1	1
Less than 12 months Fair Value	5	5
Less than 12 months Unrealized Losses	0	1
12 months or longer Fair Value	0	0
12 months or longer Unrealized Losses	$ 1	$ 0