Derivative Instruments Fair Value and Offsets Table (Details) - USD ($) $ in Thousands		Sep. 30, 2016		Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	[1]	$ 24
Derivative Asset, Fair Value, Gross Asset		3,256		$ 1,388
Derivative Asset, Fair Value, Gross Liability		(269)		(984)
Derivative Asset, Fair Value, Amount Offset Against Collateral		2,987		404
Derivative Liability, Fair Value, Gross Liability		245		5,956
Derivative Liability, Fair Value, Gross Asset		(245)		(984)
Derivative Liability, Fair Value, Amount Offset Against Collateral		0		4,972
Financial Swaps | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		3,256		999
Derivative Asset, Fair Value, Gross Liability		(269)	[2]	(785)
Derivative Asset, Fair Value, Amount Offset Against Collateral		2,987		214
Derivative Liability, Fair Value, Gross Liability		245		785
Derivative Liability, Fair Value, Gross Asset		(245)		(785)
Derivative Liability, Fair Value, Amount Offset Against Collateral		$ 0		0
Financial Swaps | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset				177
Derivative Asset, Fair Value, Gross Liability				(177)
Derivative Asset, Fair Value, Amount Offset Against Collateral				0
Derivative Liability, Fair Value, Gross Liability				5,146
Derivative Liability, Fair Value, Gross Asset				(177)
Derivative Liability, Fair Value, Amount Offset Against Collateral				4,969
Financial Swaps | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset				148
Derivative Asset, Fair Value, Gross Liability				(22)
Derivative Asset, Fair Value, Amount Offset Against Collateral				126
Derivative Liability, Fair Value, Gross Liability				22
Derivative Liability, Fair Value, Gross Asset				(22)
Derivative Liability, Fair Value, Amount Offset Against Collateral				0
Forward contracts | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset				64
Derivative Asset, Fair Value, Gross Liability				0
Derivative Asset, Fair Value, Amount Offset Against Collateral				64
Forward contracts | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability				3
Derivative Liability, Fair Value, Gross Asset				0
Derivative Liability, Fair Value, Amount Offset Against Collateral				$ 3

[1] Excludes unrealized gains or losses on derivatives, which are recorded on the balance sheet as regulatory assets or regulatory liabilities.

[2] Current asset derivative amount offset includes $24 thousand of collateral payable for the period ending September 30, 2016.