INCOME TAXES (The Significant Components of Deferred Income Tax Assets and Liabilities) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Gross Deferred Income Tax Assets
Finance Lease Obligations	$ 21,000,000
Finance Lease Obligations		$ 48,000,000
Operating Loss Carryforwards, Net	3,000,000	23,000,000
Customer Advances and Contributions in Aid of Construction	19,000,000	16,000,000
AMT Credit	7,000,000	13,000,000
Other Postretirement Benefits	15,000,000	15,000,000
Investment Tax Credit Carryforward	34,000,000	34,000,000
Income Taxes Recoverable Through Future Rates	81,000,000	87,000,000
Other	79,000,000	60,000,000
Total Gross Deferred Income Tax Assets	259,000,000	296,000,000
Deferred Tax Assets Valuation Allowance	0	0
Gross Deferred Income Tax Liabilities
Plant, Net	(602,000,000)	(552,000,000)
Plant Abandonments	(17,000,000)	(18,000,000)
Finance Lease Assets, Net	(18,000,000)	(44,000,000)
Pensions	(17,000,000)	(19,000,000)
Income Taxes Payable Through Future Rates	(9,000,000)	(12,000,000)
Other	(28,000,000)	(21,000,000)
Total Gross Deferred Income Tax Liabilities	(691,000,000)	(666,000,000)
Deferred Income Taxes, Net	$ (432,000,000)	$ (370,000,000)