Derivatives And Risk Management Derivatives and Risk Management (Collateral) (Details) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Derivative, Fair Value, Amount Offset Against Collateral, Net	$ 48,862,000	$ 44,390,000
Interest Rate Contracts [Member]
Derivative [Line Items]
Liability position at aggregate fair value	88,975,000	77,568,000
Additional Collateral, Aggregate Fair Value	21,330,000	19,404,000
Commodity Contracts [Member]
Derivative [Line Items]
Liability position at aggregate fair value	8,436,000	12,911,000
Additional Collateral, Aggregate Fair Value	8,433,000	16,227,000
Letters of credit outstanding	26,200,000	14,500,000
Derivative, Fair Value, Amount Offset Against Collateral, Net	12,592,000	15,510,000
Collateral Already Posted, Aggregate Fair Value	23,093,000	20,565,000
Interest Rate Swap [Member]
Derivative [Line Items]
Letters of credit outstanding	10,700,000	10,900,000
Derivative, Fair Value, Amount Offset Against Collateral, Net	36,270,000	28,880,000
Collateral Already Posted, Aggregate Fair Value	$ 36,270,000	28,880,000
Other Current Assets [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Derivative, Fair Value, Amount Offset Against Collateral, Net		$ 0