Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Components of the income tax provision applicable to federal, state and foreign income taxes for the years ended December 31, 2016, 2015 and 2014 are as follows (in thousands):

	2016			2015			2014
Federal income tax expense (benefit):
Current	$	(24,777	)	$	(42,020	)	$	39,438
Deferred		(134,592	)		(83,812	)		39,673
		(159,369	)		(125,832	)		79,111
State income tax expense (benefit):
Current		(257	)		(3,480	)		3,987
Deferred		(14,163	)		(12,433	)		5,292
		(14,420	)		(15,913	)		9,279
Foreign income tax expense (benefit):
Current		(368	)		(2,590	)		4,521
Deferred		(3,405	)		(3,628	)		(1,292	)
		(3,773	)		(6,218	)		3,229
Total income tax expense (benefit):
Current		(25,402	)		(48,090	)		47,946
Deferred		(152,160	)		(99,873	)		43,673
Total income tax expense (benefit):	$	(177,562	)	$	(147,963	)	$	91,619

Difference Between Statutory Federal Income Tax Rate and Effective Income Tax Rate

The difference between the statutory federal income tax rate and the effective income tax rate for the years ended December 31, 2016, 2015 and 2014 is summarized as follows:

	2016			2015			2014
Statutory tax rate		35.0	%		35.0	%		35.0	%
State income taxes		2.0			2.1			2.5
Permanent differences		(0.1	)		(1.3	)		(1.4	)
Other differences, net		(1.1	)		(2.4	)		(0.1	)
Effective tax rate		35.8	%		33.4	%		36.0	%

Tax Effect of Significant Temporary Differences Representing Deferred Tax Assets and Liabilities

The tax effect of significant temporary differences representing deferred tax assets and liabilities at December 31, 2016 and 2015 are as follows (in thousands):

	2016			2015
Deferred tax assets:
Current:
Net operating loss carryforwards	$	4,702		$	27,887
Workers’ compensation allowance		25,736			28,734
Other		16,710			21,305
		47,148			77,926
Non-current:
Net operating loss carryforwards		198,783			77,514
AMT credit		7,907			—
Expense associated with employee stock options		14,443			14,591
Federal benefit of state deferred tax liabilities		23,026			24,485
Other		19,137			20,441
		263,296			137,031
Less:
Allowance to reduce deferred tax asset to expected realizable value		—			(603	)
Total deferred tax assets		310,444			214,354
Deferred tax liabilities:
Current:
Other		(10,709	)		(12,805	)
Non-current:
Property and equipment basis difference		(929,483	)		(986,922	)
Other		(16,789	)		(13,339	)
		(946,272	)		(1,000,261	)
Total deferred tax liabilities		(956,981	)		(1,013,066	)
Net deferred tax liability	$	(646,537	)	$	(798,712	)