INCOME TAXES (Reconciliation of Differences between Income Tax Expense and Amount Obtained by Multiplying Pre-Tax Income by U.S. Statutory Federal Income Tax Rate) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal Income Tax Expense at Statutory Rate	$ 49,000	$ 49,000	$ 46,000
State Income Tax Expense, Net of Federal Deduction	9,000	9,000	9,000
Federal/State Tax Credits	(10,000)	(3,000)	(6,000)
Allowance for Equity Funds Used During Construction	(3,000)	(7,000)	(3,000)
Excess Deferred Income Taxes	(14,000)	(7,000)	(9,000)
Impact of AMT Sequestration	0	0	(2,000)
Other	1,000	0	(1,000)
Total Income Tax Expense	32,476	$ 41,452	$ 34,053
Tax credit benefits	$ 7,000