NATURE OF OPERATIONS AND FINANCIAL STATEMENT PRESENTATION (Reclassification) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Other Income (Deductions)
Interest Income		$ 0		$ 0
Other Income		0		0
Other Expense		0		0
Appreciation in Value of Investments		0		0
Allowance For Equity Funds	$ 2,113	1,353	$ 5,290	4,145
Other, Net	1,702	255	2,957	8,562
Interest Expense
Long-Term Debt		0		0
Capital Leases		0		0
Other Interest Expense		0		0
Interest Capitalized	(757)	(525)	(2,150)	(1,645)
Interest Expense	$ 16,626	16,291	$ 49,818	48,972
Previously Reported
Other Income (Deductions)
Interest Income		30		556
Other Income		1,738		12,630
Other Expense		(1,072)		(2,609)
Appreciation in Value of Investments		912		2,130
Allowance For Equity Funds		0		0
Other, Net		0		0
Interest Expense
Long-Term Debt		15,531		46,461
Capital Leases		613		1,941
Other Interest Expense		147		570
Interest Expense		0		0
Restatement Adjustment
Other Income (Deductions)
Interest Income		(30)		(556)
Other Income		(1,738)		(12,630)
Other Expense		1,072		2,609
Appreciation in Value of Investments		(912)		(2,130)
Allowance For Equity Funds		1,353		4,145
Other, Net		255		8,562
Interest Expense
Long-Term Debt		(15,531)		(46,461)
Capital Leases		(613)		(1,941)
Other Interest Expense		(147)		(570)
Interest Expense		16,291		48,972
Interest Capitalized
Interest Expense
Interest Capitalized		0		0
Interest Capitalized | Previously Reported
Interest Expense
Interest Capitalized		(525)		(1,645)
Interest Capitalized | Restatement Adjustment
Interest Expense
Interest Capitalized		525		1,645
Allowance For Borrowed Funds
Interest Expense
Interest Capitalized		(525)		(1,645)
Allowance For Borrowed Funds | Previously Reported
Interest Expense
Interest Capitalized		0		0
Allowance For Borrowed Funds | Restatement Adjustment
Interest Expense
Interest Capitalized		$ (525)		$ (1,645)