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	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Credit Derivatives [Line Items]
Maximum potential risk	$ (382)	$ (381)
Estimated fair value	(82)	(130)
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	0	0
Estimated fair value	0	0
Three to five years
Credit Derivatives [Line Items]
Maximum potential risk	(147)	(146)
Estimated fair value	0	(17)
Five to ten years
Credit Derivatives [Line Items]
Maximum potential risk	(235)	(235)
Estimated fair value	(82)	(113)
A
Credit Derivatives [Line Items]
Credit Rating	A	A
Maximum potential risk	(147)	(146)
Estimated fair value	0	(17)
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	0	0
Estimated fair value	0	0
A | Three to five years
Credit Derivatives [Line Items]
Maximum potential risk	(147)	(146)
Estimated fair value	0	(17)
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	(235)	(235)
Estimated fair value	(82)	(113)
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	0	0
Estimated fair value	0	0
BB or Lower | Five to ten years
Credit Derivatives [Line Items]
Maximum potential risk	(235)	(235)
Estimated fair value	$ (82)	$ (113)