DERIVATIVE INSTRUMENTS - Maximum Potential Risk, Fair Value, Weighted-Average Years to Maturity, and Underlying Referenced Credit Obligation Type for Credit Default Swaps (Detail) (Corporate Bonds, USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Credit Derivatives [Line Items]
Maximum potential risk	$ 337	$ (355)
Estimated fair value	(54)	(65)
Less than one year
Credit Derivatives [Line Items]
Maximum potential risk	0	0
Estimated fair value	0	0
One to three years
Credit Derivatives [Line Items]
Maximum potential risk	124	(133)
Estimated fair value	2	2
Three to five years
Credit Derivatives [Line Items]
Maximum potential risk	106	(106)
Estimated fair value	(41)	(47)
Five to ten years
Credit Derivatives [Line Items]
Maximum potential risk	107	(116)
Estimated fair value	(15)	(20)
A
Credit Derivatives [Line Items]
Credit Rating	A	A
Maximum potential risk	124	(133)
Estimated fair value	2	2
A | Less than one year
Credit Derivatives [Line Items]
Maximum potential risk	0	0
Estimated fair value	0	0
A | One to three years
Credit Derivatives [Line Items]
Maximum potential risk	124	(133)
Estimated fair value	2	2
A | Three to five years
Credit Derivatives [Line Items]
Maximum potential risk	0	0
Estimated fair value	0	0
A | Five to ten years
Credit Derivatives [Line Items]
Maximum potential risk	0	0
Estimated fair value	0	0
BB or Lower
Credit Derivatives [Line Items]
Credit Rating	BB or lower	BB or lower
Maximum potential risk	213	(222)
Estimated fair value	(56)	(67)
BB or Lower | Less than one year
Credit Derivatives [Line Items]
Maximum potential risk	0	0
Estimated fair value	0	0
BB or Lower | One to three years
Credit Derivatives [Line Items]
Maximum potential risk	0	0
Estimated fair value	0	0
BB or Lower | Three to five years
Credit Derivatives [Line Items]
Maximum potential risk	106	(106)
Estimated fair value	(41)	(47)
BB or Lower | Five to ten years
Credit Derivatives [Line Items]
Maximum potential risk	107	(116)
Estimated fair value	$ (15)	$ (20)