Business Segment Information (Summary Of Company's Reporting Segments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
REVENUES	$ 1,481,643	$ 1,450,505	$ 1,349,588
Depreciation and amortization	240,314	232,332	208,451
Interest Expense	121,771	95,509	101,130
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	167,921	147,474	157,744
Property, Plant and Equipment, Additions	219,242	235,764	228,861
Tax benefit	35,528	13,449	48,951
Net income	132,393	134,025	108,793
TOTAL ASSETS	4,928,669	4,862,053	4,740,561
Accruals for capital expenditures	35,471	47,553	45,322
Electric [Member]
Segment Reporting Information [Line Items]
REVENUES	1,481,643	1,450,505	1,349,588
Depreciation and amortization	240,314	232,332	208,451
Interest Expense	89,014	64,472	65,340
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	200,707	178,953	202,106
Property, Plant and Equipment, Additions		235,764	228,861
TOTAL ASSETS	4,918,408	4,851,712	4,719,547
Other Segments [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	0	0	0
Interest Expense	32,757	31,037	35,790
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(32,786)	(31,479)	(44,362)
Property, Plant and Equipment, Additions	0	0	0
TOTAL ASSETS	$ 10,261	$ 10,341	$ 21,014