Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Schedule of income before income tax, domestic and foreign [Table Text Block]

Income before income taxes was attributable to the following sources:

	Year Ended December 31,
	2016		2015		2014
United States	$	35,867	$	32,807	$	30,380
Canada	1,377		2,451		7,920
Total	$	37,244	$	35,258	$	38,300

Schedule of components of income tax expense (benefit) [Table Text Block]

The provision for income taxes follows:

	Year Ended December 31,
	2016		2015			2014
Currently payable:
Federal	$	12,216	$	13,337		$	13,159
State	2,286		2,487			2,524
Canadian	398		611			2,127
Total current	14,900		16,435			17,810
Deferred taxes	60		(2,975		)	(2,679		)
Total taxes on income	$	14,960	$	13,460		$	15,131

Schedule of effective income tax rate reconciliation [Table Text Block]

A reconciliation of the expected statutory U.S. federal rate to our actual effective income tax rate follows:

	Year Ended December 31,
	2016		2015		2014
Statutory U.S. federal tax rate	35.0	%	35.0	%	35.0	%
State income taxes, net of federal benefit	4.0		3.7		3.9
Effect of Canadian income taxes	(.2	)	(.5	)	(1.7	)
Nondeductible expenses	2.2		2.3		1.9
ESOP dividend deduction	(.7	)	(.8	)	(.7	)
Uncertain tax adjustments and audit settlement	.2		1.5		1.6
Valuation allowance	—		(2.2	)	—
All other, net	(.3	)	(.8	)	(.5	)
Effective income tax rate	40.2	%	38.2	%	39.5	%

Deferred tax assets and liabilities, noncurrent [Table Text Block]

Significant components of our noncurrent net deferred tax assets and liabilities at December 31, were as follows:

	December 31,
	2016		2015
Deferred tax assets:
Self-insurance accruals	$	21,967	$	21,136
Accrued compensated absences	3,540		3,189
Accrued expenses and other liabilities	1,394		1,255
Accrued stock compensation	2,502		2,144
Defined benefit pension plans	4,019		3,721
Foreign tax credit carryforward	575		680
Other future deductible amounts, net	4,213		4,354
	38,210		36,479
Deferred tax liabilities:
Intangibles	297		150
Prepaid expenses	3,510		3,138
Property and equipment	23,274		21,670
	27,081		24,958
Net deferred tax assets--noncurrent	$	11,129	$	11,521

Summary of income tax contingencies [Table Text Block]

The balance of unrecognized benefits and the amount of related interest and penalties at December 31, were as follows:

	December 31,
	2016		2015
Unrecognized tax benefits	$	2,532	$	2,557
Portion, if recognized, would reduce tax expense and effective tax rate	2,053		1,981
Accrued interest on unrecognized tax benefits	107		115

Schedule of unrecognized tax benefits roll forward [Table Text Block]

The changes in our unrecognized tax benefits are summarized in the table below:

	Year Ended December 31,
	2016			2015			2014
Balance, beginning of year	$	2,557		$	1,949		$	1,221
Additions based on tax positions related to the current year	402			642			587
Additions for tax positions of prior years	51			52			234
Reductions for tax positions of prior years	(39		)	(63		)	(79		)
Lapses in statutes of limitations	(439		)	(23		)	(14		)
Balance, end of year	$	2,532		$	2,557		$	1,949