Accumulated Other Comprehensive Income (Loss) Accumulated Other comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Loss (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period	$ (2,533)	$ (5,062)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(3,724)	2,251
Amounts reclassified from accumulated other comprehensive loss	581	278
Net current-period other comprehensive loss	(3,143)	2,529
Accumulated other comprehensive loss at end of period	(5,676)	(2,533)
UnrealizedGainsLossesFromDefinedBenefitPensionAndPostretirementPlanItems [Member]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period	(2,533)	(5,062)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(3,242)	2,251
Amounts reclassified from accumulated other comprehensive loss	132	278
Net current-period other comprehensive loss	(3,110)	2,529
Accumulated other comprehensive loss at end of period	(5,643)	(2,533)
Accumulated (Gain) Loss from Commodity Contracts Cash Flows Hedges [Member]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period	0	0
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(482)	0
Amounts reclassified from accumulated other comprehensive loss	449	0
Net current-period other comprehensive loss	(33)	0
Accumulated other comprehensive loss at end of period	$ (33)	$ 0