Derivatives And Risk Management (Derivative Instruments Summary) (Details) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Gross Asset	$ 77,135,000	$ 99,045,000
Gross Liability	(216,032,000)	(229,790,000)
Collateral Netting	48,862,000	44,390,000
Net Asset (Liability) in Balance Sheet	(90,035,000)	(86,355,000)
Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Collateral Netting	12,592,000	15,510,000
Other Current Liabilities [Member] | Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	8,000	1,000
Gross Liability	(73,000)	(21,000)
Collateral Netting	0	0
Net Asset (Liability) in Balance Sheet	(65,000)	(20,000)
Other Current Liabilities [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	0	0
Gross Liability	(7,344,000)	(7,325,000)
Collateral Netting	0	0
Net Asset (Liability) in Balance Sheet	(7,344,000)	(7,325,000)
Other Current Assets [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset		966,000
Gross Liability		(506,000)
Collateral Netting		0
Net Asset (Liability) in Balance Sheet		460,000
Current Utility Energy Commodity Derivative Assets [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	900,000	2,063,000
Gross Liability	(1,000)	(538,000)
Collateral Netting	0	0
Net Asset (Liability) in Balance Sheet	899,000	1,525,000
Current Utility Energy Commodity Derivative Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	60,218,000	66,421,000
Gross Liability	(77,958,000)	(97,586,000)
Collateral Netting	2,648,000	13,120,000
Net Asset (Liability) in Balance Sheet	(15,092,000)	(18,045,000)
Other Noncurrent Liabilities [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	1,002,000	0
Gross Liability	(81,631,000)	(69,737,000)
Collateral Netting	36,270,000	28,880,000
Net Asset (Liability) in Balance Sheet	(44,359,000)	(40,857,000)
Other Noncurrent Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	15,007,000	29,594,000
Gross Liability	(49,025,000)	(54,077,000)
Collateral Netting	9,944,000	2,390,000
Net Asset (Liability) in Balance Sheet	$ (24,074,000)	$ (22,093,000)