Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

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):

	2015			2014
Depreciation	$	103,471		$	100,607
Other		3,482			(559	)
Gross deferred tax liabilities		106,953			100,048
Allowance for doubtful accounts		(1,350	)		(1,511	)
Equity-based compensation		(3,961	)		(3,440	)
Employee benefits		(4,847	)		(7,024	)
Claims and insurance		(20,942	)		(22,019	)
Other		(8,436	)		(7,108	)
Gross deferred tax assets		(39,536	)		(41,102	)
Net deferred tax liability	$	67,417		$	58,946

Summary of Income Tax Provision (Benefit)

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

	2015			2014			2013
Current:
U.S. federal	$	20,768		$	18,085		$	9,924
State		1,759			1,690			2,496
Total current income tax provision		22,527			19,775			12,420
Deferred:
U.S. federal		8,570			9,547			11,822
State		(150	)		(85	)		276
Total deferred income tax provision		8,420			9,462			12,098
Total income tax provision	$	30,947		$	29,237		$	24,518

Summary of Reconciliation Between Income Taxes and Effective Income Tax Provision

A reconciliation between income taxes at the federal statutory rate (35 percent) and the effective income tax provision is as follows (in thousands):

	2015			2014			2013
Provision at federal statutory rate	$	30,087		$	28,430		$	23,851
State income taxes, net		2,229			2,426			2,574
Nondeductible business expenses		696			589			675
Tax credits		(1,532	)		(1,434	)		(2,429	)
Other, net		(533	)		(774	)		(153	)
Total provision	$	30,947		$	29,237		$	24,518

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):

	2015			2014
Gross unrecognized tax benefits at beginning of year	$	1,165		$	1,281
Gross decreases in tax positions for prior years		—			—
Gross increases in tax positions for current year		237			202
Settlements		—			—
Lapse of statute of limitations		(244	)		(318	)
Gross unrecognized tax benefits at end of year	$	1,158		$	1,165