Fair Value (Reconciliation For All Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Significant Unobservable Inputs (Level 3)) (Details) - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ (2,976)	$ (5,262)	$ (16,409)	$ (19,334)
Included in regulatory assets/liabilities	8,610	5,353	(4,382)
Settlements	(6,324)	5,794	7,307
Transfers, Net	0	0	0
Gain (Loss) Included in Earnings	0	0	0
Gain (Loss) Included in Other Comprehensive Income (Loss)	0	0	0
Purchases	0	0	0
Issuances	0	0	0
Natural Gas Exchange Agreements [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	(2,976)	(2,774)	(3,164)	(5,885)
Included in regulatory assets/liabilities	8,175	326	3,292
Settlements	(8,377)	64	(571)
Transfers, Net	0	0	0
Gain (Loss) Included in Earnings	0	0	0
Gain (Loss) Included in Other Comprehensive Income (Loss)	0	0	0
Purchases	0	0	0
Issuances	0	0	0
Power Exchange Agreements [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	0	(2,488)	(13,245)	$ (13,449)
Included in regulatory assets/liabilities	435	5,027	(7,674)
Settlements	2,053	5,730	7,878
Transfers, Net	0	0	0
Gain (Loss) Included in Earnings	0	0	0
Gain (Loss) Included in Other Comprehensive Income (Loss)	0	0	0
Purchases	0	0	0
Issuances	$ 0	$ 0	$ 0