Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Summary of Deferred Tax Liabilities and Assets

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Deferred tax liabilities (assets) are comprised of the following at December 31 (in thousands):

	2021			2020
Depreciation	$	165,405		$	153,573
Leases		27,876			29,036
Other		4,658			3,545
Gross deferred tax liabilities		197,939			186,154
Allowance for doubtful accounts		(1,374	)		(1,325	)
Equity-based compensation		(3,626	)		(3,059	)
Employee benefits		(8,516	)		(5,869	)
Leases		(27,357	)		(29,028	)
Claims and insurance		(27,351	)		(22,704	)
Other		(5,578	)		(4,351	)
Gross deferred tax assets		(73,802	)		(66,336	)
Net deferred tax liability	$	124,137		$	119,818

Summary of Income Tax Provision

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

	2021		2020		2019
Current:
U.S. federal	$	62,222	$	24,311	$	5,095
State		12,997		5,364		3,176
Total current income tax provision		75,219		29,675		8,271
Deferred:
U.S. federal		3,915		8,255		24,137
State		404		8		525
Total deferred income tax provision		4,319		8,263		24,662
Total income tax provision	$	79,538	$	37,938	$	32,933

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 effective income tax provision is as follows (in thousands):

	2021			2020			2019
Provision at federal statutory rate	$	69,856		$	37,018		$	30,797
State income taxes, net of federal benefit		11,435			5,664			5,106
Tax credits		(1,754	)		(1,424	)		(2,249	)
Excess tax benefit on stock compensation (1)		(793	)		(4,500	)		(1,471	)
Other, net		794			1,180			750
Total provision	$	79,538		$	37,938		$	32,933

(1) In accordance with ASC Topic 718, these excess tax benefits on stock compensation are reported as a financing cash flow, rather than as an operating cash flow.

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):

	2021			2020
Gross unrecognized tax benefits at beginning of year	$	1,052		$	957
Gross (decreases) increases in tax positions for prior years		(4	)		(2	)
Gross increases in tax positions for current year		598			236
Settlements		(96	)		—
Lapse of statute of limitations		(180	)		(139	)
Gross unrecognized tax benefits at end of year	$	1,370		$	1,052