GENERAL (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended			3 Months Ended			3 Months Ended			3 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2008	Mar. 31, 2011 Change In Accounting Principle, As Originally Reported [Member]	Dec. 31, 2011 Change In Accounting Principle, As Originally Reported [Member]		Mar. 31, 2011 Change In Accounting Principle, Adjustments [Member]	Dec. 31, 2011 Change In Accounting Principle, Adjustments [Member]		Mar. 31, 2011 Change In Accounting Principle, Retrospectively Adjusted [Member]	Dec. 31, 2011 Change In Accounting Principle, Retrospectively Adjusted [Member]
Effect of Change in Accounting Principle [Line Items]
Change In Accounting Principle, Depreciation And Amortization				$ 231			$ (1)			$ 230
Change In Accounting Principle, Income Before Income Taxes And Equity Earnings Of Certain Unconsolidated Subsidiaries				342			1			343
Change In Accounting Principle, Income Tax Expense				109			5			114
Change In Accounting Principle, Net Income				264			(4)			260
Change In Accounting Principle, Earnings				258			(4)			254
Change In Accounting Principle, Basic Earnings Per Common Share				$ 1.07			$ (0.01)			$ 1.06
Change In Accounting Principle, Diluted Earnings Per Common Share				$ 1.07			$ (0.02)			$ 1.05
Change In Accounting Principle, Deferred Income Taxes And Invesment Tax Credits				88			(6)			82
Change In Accounting Principle, Net Change In Other Working Capital Components (Income Taxes)				286			11			297
Change In Accounting Principle, Income Taxes Payable					16			(11)			5
Change In Accounting Principle, Deferred Credits And Other					783			1			784
Change In Accounting Principle, Deferred Income Taxes, Noncurrent Liability					1,554			(34)			1,520
Change In Accounting Principle, Property Plant And Equipment					31,303			(111)			31,192
Change In Accounting Principle, Less Accumulated Depreciation And Amortization					7,731			(4)			7,727
Change In Accounting Principle Property Plant And Equipment Net					23,572			(107)			23,465
Change In Accounting Principle, Retained Earnings					8,225	[1]		(63)	[1]		8,162	[1]
Cumulative Effect of Change in Accounting Principle [Abstract]
Cumulative Effect of Change In Accounting Principle Of Reductions In Net Income And Earnings	26	30	7
Retained Earnings Cumulative Effect Of Change In Accounting Principle Net Of Tax		$ 37

[1] Adjustment includes the cumulative effect of the change in accounting principle of reductions in net income and earnings of $26 million, $30 million, a negligible amount, and $7 million for the years ended December 31, 2011, 2010, 2009 and 2008, respectively.