Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of Income Tax Expense

Income tax expense consisted of the following (in thousands):

	Years Ended December 31,
	2017			2016		2015
Current:
Federal	$	38,535		$	237	$	32,090
State	3,979			2,928		5,665
Foreign	102			534		1,250
	42,616			3,699		39,005
Deferred:
Federal	(104,573		)	42,895		33,912
State	3,625			1,737		4,530
	(100,948		)	44,632		38,442
Total income tax expense (benefit)	$	(58,332	)	$	48,331	$	77,447

Schedule of Effective Income Tax Rate Reconciliation

The effective income tax rate differs from the federal corporate tax rate of 35% in 2017, 2016 and 2015 as follows (in thousands):

	Years Ended December 31,
	2017			2016				2015
Tax at statutory rate	$	50,595		$	44,611			$	70,406
Change in federal income tax rate	(110,508		)	—			—	—
State income taxes, net of federal tax benefits	4,943			3,032				6,627
Non-deductible meals and entertainment	1,495			1,549				1,687
Income tax credits	(1,780		)	(1,900		)		(1,700		)
Equity compensation	(820		)	—			—	—
Other, net	(2,257		)	1,039				427
Total income tax expense (benefit)	$	(58,332	)	$	48,331			$	77,447

Schedule of Deferred Tax Assets and Liabilities

At December 31, deferred income tax assets and liabilities consisted of the following (in thousands):

	December 31,
	2017		2016
Deferred income tax assets:
Insurance and claims accruals	$	41,986	$	74,015
Compensation-related accruals	6,797		10,056
Allowance for uncollectible accounts	3,599		6,135
Other	1,979		4,168
Gross deferred income tax assets	54,361		94,374
Deferred income tax liabilities:
Property and equipment	243,482		377,093
Prepaid expenses	4,699		7,737
Other	1,367		2,313
Gross deferred income tax liabilities	249,548		387,143
Net deferred income tax liability	$	195,187	$	292,769

Reconciliation of Unrecognized Tax Benefits

The reconciliations of beginning and ending gross balances of unrecognized tax benefits for 2017 and 2016 are shown below (in thousands).

	December 31,
	2017			2016
Unrecognized tax benefits, beginning balance	$	6,055		$	7,717
Gross increases – tax positions in prior period	168			236
Gross decreases – tax positions in prior period	—			(217		)
Gross increases – current-period tax positions	136			473
Settlements	(3,476		)	(2,154		)
Unrecognized tax benefits, ending balance	$	2,883		$	6,055