Stockholder's Equity - Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Loss (Detail) - USD ($) shares in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		$ (1,379,000)		$ (1,379,000)	$ 1,303,000
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				(1,433,000)	2,206,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				(247,000)	(2,139,000)
Net current-period other comprehensive income (loss)	$ (1,076,000)		$ (480,000)	(1,680,000)	67,000
Ending balance	(3,059,000)		1,370,000	(3,059,000)	1,370,000
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)		(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				21,000	35,000
Net current-period other comprehensive income (loss)				21,000	35,000
Ending balance	(2,485,000)		(3,233,000)	(2,485,000)	(3,233,000)
Accumulated (Gain) Loss from Commodity Contracts Cash Flows Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		1,092,000		1,092,000	4,571,000
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(2,065,000)		(293,000)	(2,045,000)	2,206,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	313,000		(205,000)	(126,000)	(2,174,000)
Net current-period other comprehensive income (loss)				(2,171,000)	32,000
Ending balance	(1,079,000)		4,603,000	(1,079,000)	4,603,000
Accumulated (Gain) Loss from Interest Rate Swap Cash Flows Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		$ 35,000		35,000	0
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	758,000		0	612,000	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				(142,000)	0
Net current-period other comprehensive income (loss)				470,000	0
Ending balance	$ 505,000		$ 0	$ 505,000	$ 0