Derivatives And Risk Management (Energy Commodity Derivatives) (Details) frequency in Thousands, Volt in Thousands	12 Months Ended
	Dec. 31, 2018 frequency Volt	Dec. 31, 2017 frequency Volt
Sales [Member] | Electric Derivative [Member] | Physical [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Settled in 1 Year	197	213
Settled in 2 Years	123	94
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	2,790	1,739
Settled in 2 Years	959	1,420
Settled in 3 Years	0	589
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	2,909	3,643
Settled in 2 Years | Volt	1,430	1,345
Settled in 3 Years | Volt	1,049	1,430
Settled in 4 Years	0	1,049
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	54,418	67,375
Settled in 2 Years | Volt	14,625	35,438
Settled in 3 Years | Volt	4,100	915
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	206	426
Settled in 2 Years	0	235
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	941	763
Settled in 2 Years	0	737
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	10,732	10,572
Settled in 2 Years | Volt	1,138	610
Settled in 3 Years | Volt	0	910
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	101,293	107,580
Settled in 2 Years | Volt	47,225	61,073
Settled in 3 Years | Volt	9,670	16,590
Settled in 4 Years | Volt	0	0
Settled in 5 Years | Volt	0	0
Thereafter | Volt	0	0