Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Summary of Income Tax Provision

The income tax provision consists of the following (in thousands):

	2023			2022		2021
Current:
U.S. federal	$	82,802		$	68,934	$	62,222
State		18,498			20,058		12,997
Total current income tax provision		101,300			88,992		75,219
Deferred:
U.S. federal		10,345			21,440		3,915
State		(275	)		194		404
Total deferred income tax provision		10,070			21,634		4,319
Total income tax provision	$	111,370		$	110,626	$	79,538

Summary of Reconciliation Between Income Taxes and Effective Income Tax Provision

A reconciliation between income taxes at the federal statutory rate (21 percent) and the actual income tax provision is as follows (in thousands):

	2023			2022			2021
Provision at federal statutory rate	$	97,908		$	98,290		$	69,856
State income taxes, net of federal benefit		15,580			16,274			11,435
Tax credits		(1,181	)		(1,355	)		(1,754	)
Excess tax benefit on stock compensation		(1,004	)		(1,578	)		(793	)
Other, net		67			(1,005	)		794
Total provision	$	111,370		$	110,626		$	79,538

Summary of Deferred Tax Liabilities and Assets

Deferred tax (liabilities) assets are comprised of the following at December 31 (in thousands):

	2023			2022
Depreciation	$	(196,494	)	$	(183,276	)
Leases		(29,361	)		(30,886	)
Other		(6,022	)		(5,471	)
Gross deferred tax liabilities		(231,877	)		(219,633	)
Allowance for credit losses		1,097			1,435
Equity-based compensation		4,834			4,089
Employee benefits		12,014			9,988
Leases		30,227			30,578
Claims and insurance		21,597			22,137
Other		6,982			6,377
Gross deferred tax assets		76,751			74,604
Valuation Allowance		(715	)		(742	)
Net deferred tax assets		76,036			73,862
Net deferred tax liability	$	(155,841	)	$	(145,771	)

Summary of Gross Unrecognized Tax Benefits

A reconciliation of the beginning and ending total amounts of gross unrecognized tax benefits is as follows (in thousands):

	2023			2022
Gross unrecognized tax benefits at beginning of year	$	3,867		$	1,370
Gross increases in tax positions for prior years		2			1,779
Gross increases in tax positions for current year		1,077			1,005
Settlements		—			—
Lapse of statute of limitations		(254	)		(287	)
Gross unrecognized tax benefits at end of year	$	4,692		$	3,867