Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Loss (Detail) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax [Roll Forward]
Beginning balance	$ (2,533,000)	$ (5,062,000)
Other comprehensive loss before reclassifications	(28,000)	(6,000)
Amounts reclassified from accumulated other comprehensive loss	(92,000)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	92,000	165,000
Net current-period other comprehensive income (loss)	64,000	159,000
Ending balance	(2,469,000)	(4,903,000)
UnrealizedGainsLossesFromDefinedBenefitPensionAndPostretirementPlanItems [Member]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax [Roll Forward]
Beginning balance	(2,533,000)	(5,062,000)
Amounts reclassified from accumulated other comprehensive loss		(165,000)
Net current-period other comprehensive income (loss)	92,000.000	159,000
Ending balance	(2,441,000)	(4,903,000)
Accumulated (Gain) Loss from Commodity Contracts Cash Flows Hedges [Member]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax [Roll Forward]
Other comprehensive loss before reclassifications	(28,000)
Net current-period other comprehensive income (loss)	(28,000.000)
Ending balance	$ (28,000)