DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Assets:
Commodity Derivative Instruments, Assets	$ 110		$ 332
Fair Value, Measurements, Recurring [Member] | Quoted Price in Active Markets, (Level 1) [Member]
Assets:
Commodity Derivative Instruments, Assets	0		0
Commodity Derivative Instruments, Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Significant Other Inputs, (Level 2) [Member]
Assets:
Commodity Derivative Instruments, Assets	138		428
Commodity Derivative Instruments, Liabilities	87		250
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs, (Level 3) [Member]
Assets:
Commodity Derivative Instruments, Assets	0		0
Commodity Derivative Instruments, Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member]
Assets:
Commodity Derivative Instruments, Assets	138		428
Commodity Derivative Instruments, Liabilities	87		250
Fair Value, Measurements, Recurring [Member] | Netting [Member]
Assets:
Commodity Derivative Instruments, Assets	(28)	[1]	(96)	[1]
Commodity Derivative Instruments, Liabilities	(28)	[1]	(96)	[1]
Fair Value, Measurements, Recurring [Member] | Carrying Amount [Member]
Assets:
Commodity Derivative Instruments, Assets	110		332
Commodity Derivative Instruments, Liabilities	$ 59		$ 154

[1] The derivative fair values are based on analysis of each contract on a gross basis, even where the legal right of offset exists.