Derivatives And Risk Management (Energy Commodity Derivatives) (Details) frequency in Thousands, Volt in Thousands	12 Months Ended
	Dec. 31, 2019 Volt frequency	Dec. 31, 2018 Volt frequency
Sales [Member] | Electric Derivative [Member] | Physical [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Settled in 1 Year	133	197
Settled in 2 Years	0	123
Settled in 3 Years	0	0
Settled in 4 Years	0	0
Settled in 5 Years	0	0
Thereafter	0	0
Sales [Member] | Electric Derivative [Member] | Financial [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Settled in 1 Year	1,724	2,790
Settled in 2 Years	246	959
Settled in 3 Years	0	0
Settled in 4 Years	0	0
Settled in 5 Years	0	0
Thereafter	0	0
Sales [Member] | Gas Derivative [Member] | Physical [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Settled in 1 Year | Volt	2,984	2,909
Settled in 2 Years | Volt	1,040	1,430
Settled in 3 Years | Volt	0	1,049
Settled in 4 Years	0	0
Settled in 5 Years	0	0
Thereafter | Volt	0	0
Sales [Member] | Gas Derivative [Member] | Financial [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Settled in 1 Year | Volt	37,848	54,418
Settled in 2 Years | Volt	13,108	14,625
Settled in 3 Years | Volt	675	4,100
Settled in 4 Years | Volt	0	0
Settled in 5 Years	0	0
Thereafter | Volt	0	0
Purchase [Member] | Electric Derivative [Member] | Physical [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Settled in 1 Year	2	206
Settled in 2 Years	0	0
Settled in 3 Years	0	0
Settled in 4 Years	0	0
Settled in 5 Years	0	0
Thereafter	0	0
Purchase [Member] | Electric Derivative [Member] | Financial [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Settled in 1 Year	442	941
Settled in 2 Years	0	0
Settled in 3 Years	0	0
Settled in 4 Years	0	0
Settled in 5 Years	0	0
Thereafter	0	0
Purchase [Member] | Gas Derivative [Member] | Physical [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Settled in 1 Year | Volt	9,813	10,732
Settled in 2 Years | Volt	153	1,138
Settled in 3 Years | Volt	225	0
Settled in 4 Years | Volt	0	0
Settled in 5 Years | Volt	0	0
Thereafter | Volt	0	0
Purchase [Member] | Gas Derivative [Member] | Financial [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Settled in 1 Year | Volt	78,803	101,293
Settled in 2 Years | Volt	25,523	47,225
Settled in 3 Years | Volt	4,725	9,670
Settled in 4 Years | Volt	0	0
Settled in 5 Years | Volt	0	0
Thereafter | Volt	0	0