Income taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Components of Pre-tax Income and Provision for Income Taxes

	Years ended December 31,
	2021		2022		2023
	(In thousands)
Income tax expense:
Currently payable	$	5,476	$	7,130	$	7,730
Deferred income tax benefit		(321)		(688)		(720)
Total	$	5,155	$	6,442	$	7,010
Expected tax expense, at the U.S. federal statutory   income tax rate of 21%	$	4,562	$	5,736	$	6,217
State income taxes		692		827		786
Other, net		(99)		(121)		7
Total income tax expense	$	5,155	$	6,442	$	7,010

Components of Net Deferred Tax Liability

	December 31,
	2022		2023
	(In thousands)
Tax effect of temporary differences related to:
Inventories	$	369	$	373
Property and equipment		(2,188)		(1,543)
Accrued liabilities and other deductible differences		51		43
Accrued employee benefits		1,262		1,343
Goodwill		(1,693)		(1,693)
Other taxable differences		(31)		(32)
Total deferred tax liability	$	(2,230)	$	(1,509)