PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS - Pension Trusts' Net Investments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Qualified and Registered Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 4,699	$ 4,757
Qualified and Registered Pension Plans \| Fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	541	779
Qualified and Registered Pension Plans \| Fixed income \| Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	470	711
Qualified and Registered Pension Plans \| Fixed income \| Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	71	68
Qualified and Registered Pension Plans \| Fixed income \| Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Qualified and Registered Pension Plans \| Common and preferred stock and equity index instruments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	19
Qualified and Registered Pension Plans \| Common and preferred stock and equity index instruments \| Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	2
Qualified and Registered Pension Plans \| Common and preferred stock and equity index instruments \| Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	17
Qualified and Registered Pension Plans \| Common and preferred stock and equity index instruments \| Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Qualified and Registered Pension Plans \| Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,726	4,773
Qualified and Registered Pension Plans \| Investments \| Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	471	713
Qualified and Registered Pension Plans \| Investments \| Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	74	81
Qualified and Registered Pension Plans \| Investments \| Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,181	3,979
Qualified and Registered Pension Plans \| Accrued liabilities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(27)	(16)
Qualified and Registered Pension Plans \| Real estate and related funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	96	120
Qualified and Registered Pension Plans \| Real estate and related funds \| Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Qualified and Registered Pension Plans \| Real estate and related funds \| Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Qualified and Registered Pension Plans \| Real estate and related funds \| Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	96	120
Qualified and Registered Pension Plans \| Private equity and related funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,651	1,571
Qualified and Registered Pension Plans \| Private equity and related funds \| Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Qualified and Registered Pension Plans \| Private equity and related funds \| Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	(4)
Qualified and Registered Pension Plans \| Private equity and related funds \| Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,649	1,575
Qualified and Registered Pension Plans \| Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,436	2,284
Qualified and Registered Pension Plans \| Hedge funds \| Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Qualified and Registered Pension Plans \| Hedge funds \| Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Qualified and Registered Pension Plans \| Hedge funds \| Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,436	2,284
Non Registered Canadian Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15	16
Non Registered Canadian Pension Plans \| Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15	16
Non Registered Canadian Pension Plans \| Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non Registered Canadian Pension Plans \| Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non Registered Canadian Pension Plans \| Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12	11
Non Registered Canadian Pension Plans \| Cash \| Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12	11
Non Registered Canadian Pension Plans \| Cash \| Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non Registered Canadian Pension Plans \| Cash \| Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non Registered Canadian Pension Plans \| Equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	5
Non Registered Canadian Pension Plans \| Equities \| Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	5
Non Registered Canadian Pension Plans \| Equities \| Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non Registered Canadian Pension Plans \| Equities \| Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,714	4,773	4,159
Pension \| Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,181	3,979	3,915
Pension \| Real estate and related funds \| Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	96	120	122
Pension \| Private equity and related funds \| Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,649	1,575	1,473
Pension \| Hedge funds \| Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 2,436	$ 2,284	$ 2,320

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

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