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		12 Months Ended
		Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance					$ 1,303,000	$ (2,865,000)	$ (2,865,000)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax					2,206,000	5,848,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax					(2,139,000)	(2,425,000)
Net current-period other comprehensive income (loss)		$ (480,000)		$ 3,196,000	67,000	3,423,000
Ending balance		1,370,000	$ 1,303,000	558,000	$ 1,370,000	558,000	$ 1,303,000
Stock Issued During Period, Shares, Dividend Reinvestment Plan					0.1		0.1
Stock Issued During Period, Value, Dividend Reinvestment Plan					$ 137.24		$ 125.71
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan					$ 4,300,000		$ 15,200,000
Stock Issued During Period, Shares, Dividend Reinvestment Plan					0.1		0.1
Stock Issued During Period, Value, Dividend Reinvestment Plan					$ 137.24		$ 125.71
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan					4,300,000		15,200,000
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					(3,268,000)	(5,146,000)	(5,146,000)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax					0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax					35,000	128,000
Net current-period other comprehensive income (loss)					35,000	128,000
Ending balance		(3,233,000)	(3,268,000)	(5,018,000)	(3,233,000)	(5,018,000)	(3,268,000)
Accumulated (Gain) Loss from Commodity Contracts Cash Flows Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance					4,571,000	2,309,000	2,309,000
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax					2,206,000	5,825,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax					(2,174,000)	(2,534,000)
Net current-period other comprehensive income (loss)					32,000	3,291,000
Ending balance		4,603,000	4,571,000	5,600,000	4,603,000	5,600,000	4,571,000
Accumulated (Gain) Loss from Interest Rate Swap Cash Flows Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]				0	(28,000)	(28,000)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]				0	23,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]				0	(19,000)
Net current-period other comprehensive income (loss)	[1]				0	4,000
Ending balance	[1]	$ 0	$ 0	$ (24,000)	$ 0	$ (24,000)	$ 0

[1] 1) All of our interest rate swaps expired at December 31, 2021