Derivatives And Risk Management (Derivative Instruments Summary) (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Gross Asset	$ 34,027,000	$ 76,865,000
Gross Liability	(233,681,000)	(210,512,000)
Collateral Netted	82,322,000	48,556,000
Net Asset (Liability) on Balance Sheet	(117,332,000)	(85,091,000)
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Collateral Netted	64,360,000	34,030,000
Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Collateral Netted	17,962,000	14,526,000
Other Current Assets [Member] | Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	27,000
Gross Liability	(25,000)
Collateral Netted	0
Net Asset (Liability) on Balance Sheet	2,000
Other Current Assets [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	823,000	1,236,000
Gross Liability	(103,000)	(553,000)
Collateral Netted	0	0
Net Asset (Liability) on Balance Sheet	720,000	683,000
Other Current Liabilities [Member] | Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Gross Asset		2,000
Gross Liability		(19,000)
Collateral Netted		0
Net Asset (Liability) on Balance Sheet		(17,000)
Other Current Liabilities [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	0	118,000
Gross Liability	(9,033,000)	(23,262,000)
Collateral Netted	8,692,000	3,880,000
Net Asset (Liability) on Balance Sheet	(341,000)	(19,264,000)
Non-Current Interest Rate Swap Derivative Liabilities [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	386,000	1,407,000
Gross Liability	(145,737,000)	(62,236,000)
Collateral Netted	55,668,000	30,150,000
Net Asset (Liability) on Balance Sheet	(89,683,000)	(30,679,000)
Other Property And Investments Net and Other Non-current Assets[Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset		23,000
Gross Liability		0
Collateral Netted		0
Net Asset (Liability) on Balance Sheet		23,000
Current Utility Energy Commodity Derivative Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	27,159,000	67,466,000
Gross Liability	(45,815,000)	(85,409,000)
Collateral Netted	10,048,000	3,675,000
Net Asset (Liability) on Balance Sheet	(8,608,000)	(14,268,000)
Other Noncurrent Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	5,632,000	6,613,000
Gross Liability	(32,968,000)	(39,033,000)
Collateral Netted	7,914,000	10,851,000
Net Asset (Liability) on Balance Sheet	$ (19,422,000)	$ (21,569,000)