Stockholder's Equity - Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Loss (Detail) - USD ($) shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			$ (1,379,000)	$ 1,303,000
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			268,000	(460,000)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			(26,000)	(2,241,000)
Net current-period other comprehensive income (loss)	$ 1,922,000	$ (2,768,000)	242,000	(2,701,000)
Ending balance	(1,137,000)	(1,398,000)	(1,137,000)	$ (1,398,000)
Stock Issued During Period, Shares, Dividend Reinvestment Plan				0.1
Stock Issued During Period, Value, Dividend Reinvestment Plan				$ 136.26
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan				$ 4,500,000
Stock Issued During Period, Shares, Dividend Reinvestment Plan				0.1
Stock Issued During Period, Value, Dividend Reinvestment Plan				$ 136.26
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan				4,500,000
Maximum [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Proceeds from Stock Plans			75,000,000
Proceeds from Stock Plans			75,000,000
UnrealizedGainsLossesFromDefinedBenefitPensionAndPostretirementPlanItems [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(2,506,000)	(3,268,000)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			32,000	53,000
Net current-period other comprehensive income (loss)			32,000	53,000
Ending balance	(2,474,000)	(3,215,000)	(2,474,000)	(3,215,000)
Accumulated (Gain) Loss from Commodity Contracts Cash Flows Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			1,092,000	4,571,000
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	1,385,000	(2,865,000)	(660,000)	(613,000)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	328,000	(74,000)	202,000	(2,294,000)
Net current-period other comprehensive income (loss)			(458,000)	(2,907,000)
Ending balance	634,000	1,664,000	634,000	1,664,000
Accumulated (Gain) Loss from Interest Rate Swap Cash Flows Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			35,000	0
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	316,000	153,000	928,000	153,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			(260,000)	0
Net current-period other comprehensive income (loss)			668,000	153,000
Ending balance	$ 703,000	$ 153,000	$ 703,000	$ 153,000