Stock-Based Compensation (Summary Of Compensation Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation within operations and maintenance expenses	$ 1,039	$ 1,676	$ 5,444	$ 5,018
Income tax benefit	260	309	1,364	1,261
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation within operations and maintenance expenses	746	702	2,186	2,206
Income tax benefit	187	126	548	554
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation within operations and maintenance expenses	181	139	480	380
Income tax benefit	45	26	120	95
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation within operations and maintenance expenses	12	13	37	38
Income tax benefit	$ 3	4	10	11
Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation within operations and maintenance expenses		165	780	522
Income tax benefit		$ 48	$ 219	$ 151