Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Loss (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014	Jun. 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	(1,000)	(6,000)
Amounts reclassified from accumulated other comprehensive loss	(61,000)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	61,000	110,000
Net current-period other comprehensive income (loss)	60,000.000	104,000.000
Ending balance	(2,473,000)	(4,958,000)
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		(110,000)
Net current-period other comprehensive income (loss)	61,000.000	104,000.000
Ending balance	(2,472,000)	(4,958,000)
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	(1,000)
Net current-period other comprehensive income (loss)	(1,000.000)
Ending balance	$ (1,000)