INCOME TAXES (Details 2) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income taxes
Income tax deductions	$ 99,000,000	$ 85,700,000	$ 84,900,000
Valuation allowance	0
Provisional estimate		108,000,000
TCJA refund	107,000,000
TCJA gross up	42,000,000
TCJA regulatory liabilities	149,000,000
Unrecognized tax benefits that would impact effective tax rate	2,900,000
Reconciliation of the income tax expense computed by applying the current federal tax rate to pretax book income and the amount shown in the Consolidated Statements of Income
Statutory income tax	17,105,000	38,419,000	26,422,000
Increase (reduction) in taxes due to:
State income taxes net of federal tax benefit	5,685,000	6,017,000	4,341,000
Effect of regulatory treatment of fixed asset differences	(5,954,000)	(4,584,000)	(4,298,000)
Investment tax credits	(74,000)	(74,000)	(74,000)
AFUDC equity	(1,106,000)	(1,528,000)	0
Share base stock compensation	(278,000)	(581,000)	0
Other	494,000	(842,000)	425,000
Total income tax	15,872,000	$ 36,827,000	$ 26,816,000
State
Income taxes
Net operating loss resulting from repairs and maintenance deductions	28,000,000
Federal
Income taxes
Net operating loss resulting from repairs and maintenance deductions	62,400,000
California | State
Income taxes
State tax credits	4,200,000
Estimated carried-forward portion of tax credits	$ 2,300,000