Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

Deferred tax assets and liabilities as of December 31 are as follows:

	2019		2018
	(in thousands)
Deferred income tax assets:
Allowance for doubtful accounts	$	262	$	224
Accrued expenses	3,892		3,179
Stock-based compensation	178		92
Insurance accruals	15,054		15,415
State net operating loss carryforward	2,618		—
Federal net operating loss carryover and credits	8,793		—
Indirect tax benefits of unrecognized tax benefits	1,052		963
Other	3		2
Total gross deferred tax assets	31,852		19,875
Less valuation allowance	—		—
Net deferred tax assets	31,852		19,875
Deferred income tax liabilities:
Property and equipment	(101,843)		(74,794)
Goodwill and amortizable intangibles	(15,939)		(10,319)
Prepaid expenses	(1,762)		(1,268)
	(119,544)		(86,381)
Net deferred tax liability	$	(87,692)	$	(66,506)

The deferred tax amounts above have been classified in the accompanying consolidated balance sheets at December 31, 2019 and 2018 as follows:

	2019		2018
	(in thousands)
Noncurrent assets, net	$	6,006	$	4,535
Long-term liabilities, net	(93,698)		(71,041)
	$	(87,692)	$	(66,506)

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

Income tax expense consists of the following:

	2019		2018		2017
	(in thousands)
Current income taxes:
Federal	$	14,122	$	11,985	$	17,997
State	5,698		4,498		(1,495)
	19,820		16,483		16,502
Deferred income taxes:
Federal	5,595		5,537		(28,020)
State	(1,204)		(2,780)		843
	4,391		2,757		(27,177)
Total	$	24,211	$	19,240	$	(10,675)

The income tax provision differs from the amount determined by applying the U.S. federal tax rate as follows:

	2019		2018		2017
	(in thousands)
Federal tax at statutory rate (21%, 21%, 35% respectively)	$	20,406	$	19,302	$	22,574
State taxes, net of federal benefit	3,561		2,200		178
Permanent differences to return	540		408		309
Return to provision adjustment	(392)		(1,327)		(325)
Uncertain income tax penalties and interest, net	289		(1,067)		(1,208)
Enacted federal tax rate change	—		—		(32,789)
Other	(193)		(276)		586
	$	24,211	$	19,240	$	(10,675)

Reconciliation of Unrecognized Tax Benefits [Table Text Block]

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:

	2019		2018
	(in thousands)
Balance at January 1,	$	4,585	$	5,839
Additions based on tax positions related to current year	1,138		700
Additions for tax positions of prior years	124		—
Reductions due to lapse of applicable statute of limitations	(701)		(1,954)
Settlements	(136)		—
Balance at December 31,	$	5,010	$	4,585