Derivatives And Risk Management (Derivative Instruments Summary) (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Asset	$ 76,865,000	$ 99,045,000
Liability	(210,512,000)	(229,790,000)
Collateral Netting	48,556,000	44,390,000
Net Asset (Liability)	(85,091,000)	(86,355,000)
Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Collateral Netting	14,526,000	15,510,000
Collateral Already Posted, Aggregate Fair Value	28,716,000	20,565,000
Other Current Liabilities [Member] | Foreign Currency Exchange Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset	2,000	1,000
Liability	(19,000)	(21,000)
Collateral Netting	0	0
Net Asset (Liability)	(17,000)	(20,000)
Other Current Liabilities [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset	118,000	0
Liability	(23,262,000)	(7,325,000)
Collateral Netting	3,880,000	0
Net Asset (Liability)	(19,264,000)	(7,325,000)
Other Current Liabilities [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset		966,000
Liability		(506,000)
Collateral Netting		0
Net Asset (Liability)		460,000
Other Property And Investments Net [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset	23,000
Liability	0
Collateral Netting	0
Net Asset (Liability)	23,000
Current Utility Energy Commodity Derivative Assets [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Asset	1,236,000	2,063,000
Liability	(553,000)	(538,000)
Collateral Netting	0	0
Net Asset (Liability)	683,000	1,525,000
Current Utility Energy Commodity Derivative Liabilities [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Asset	67,466,000	66,421,000
Liability	(85,409,000)	(97,586,000)
Collateral Netting	3,675,000	13,120,000
Net Asset (Liability)	(14,268,000)	(18,045,000)
Other Noncurrent Liabilities [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Asset	1,407,000	0
Liability	(62,236,000)	(69,737,000)
Collateral Netting	30,150,000	28,880,000
Net Asset (Liability)	(30,679,000)	(40,857,000)
Other Noncurrent Liabilities [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Asset	6,613,000	29,594,000
Liability	(39,033,000)	(54,077,000)
Collateral Netting	10,851,000	2,390,000
Net Asset (Liability)	$ (21,569,000)	$ (22,093,000)