ASSETS HELD FOR SALE (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Apr. 24, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Disposal Group Including Discontinued Operation Additional Disclosures [Abstract]
Deferred Tax Expense From The Outside Basis Difference				$ 32
Liabilities Assumed				0	$ (2)
Termoelectrica de Mexicali [Member]
Assets Held for Sale, Assets [Abstract]
Assets Held for Sale, Cash and Cash Equivalent		$ 1		1
Assets Held for Sale, Inventories		8		8
Assets Held for Sale, Other Current Assets		21		21
Assets Held for Sale, Regulatory Assets		0		0
Assets Held for Sale, Goodwill		0		0
Assets Held for Sale, Other Assets		17		17
Assets Held for Sale, Property, Plant and Equipment, Net		250		250
Total Assets Held for Sale		297		297
Assets Held for Sale, Liabilities [Abstract]
Assets Held for Sale, Accounts Payable		1		1
Assets Held for Sale, Other Current Liabilities		6		6
Assets Held for Sale, Long-term Debt		0		0
Assets Held for Sale, Deferred Income Taxes		13		13
Assets Held for Sale, Regulatory Liabilities		0		0
Assets Held for Sale, Asset Retirement Obligations		4		4
Assets Held for Sale, Other Liabilities		19		19
Total Liabilities Held for Sale		43		43
Disposal Group Including Discontinued Operation Additional Disclosures [Abstract]
Deferred Tax Expense From The Outside Basis Difference		3		32
Deferred Tax Expense From The Outside Basis Difference After Noncontrolling Interest		2		26
Energy South [Member]
Assets Held for Sale, Assets [Abstract]
Assets Held for Sale, Cash and Cash Equivalent		1		1
Assets Held for Sale, Inventories		3		3
Assets Held for Sale, Other Current Assets		13		13
Assets Held for Sale, Regulatory Assets		12		12
Assets Held for Sale, Goodwill		72		72
Assets Held for Sale, Other Assets		53		53
Assets Held for Sale, Property, Plant and Equipment, Net		203		203
Total Assets Held for Sale		357		357
Assets Held for Sale, Liabilities [Abstract]
Assets Held for Sale, Accounts Payable		9		9
Assets Held for Sale, Other Current Liabilities		12		12
Assets Held for Sale, Long-term Debt		67		67
Assets Held for Sale, Deferred Income Taxes		38		38
Assets Held for Sale, Regulatory Liabilities		22		22
Assets Held for Sale, Asset Retirement Obligations		12		12
Assets Held for Sale, Other Liabilities		19		19
Total Liabilities Held for Sale		$ 179		$ 179
Disposal Group Including Discontinued Operation Additional Disclosures [Abstract]
Expected Cash Proceeds on Sale	$ 323
Liabilities Assumed	$ 67
Outstanding Equity Agreed To Sell, Percentage				100.00%
Mesquite Power [Member]
Disposal Group Including Discontinued Operation Additional Disclosures [Abstract]
Proceeds from Divestiture of Businesses			$ 347
Deconsolidation Gain or Loss Amount After Tax			36
Deconsolidation Gain Or Loss Amount			$ 61