Components of the income tax provision applicable to federal, state and foreign income taxes for the years ended December 31, 2019, 2018 and 2017 are as follows (in thousands):

	2019			2018			2017
Federal income tax benefit:
Current	$	(1,976	)	$	(3,954	)	$	(42	)
Deferred		(90,441	)		(35,081	)		(335,106	)
		(92,417	)		(39,035	)		(335,148	)
State income tax expense (benefit):
Current		851			1,704			(215	)
Deferred		(11,593	)		(11,147	)		4,511
		(10,742	)		(9,443	)		4,296
Foreign income tax expense (benefit):
Current		(348	)		(2,552	)		(3,108	)
Deferred		(1,168	)		5,043			249
		(1,516	)		2,491			(2,859	)
Total income tax benefit:
Current		(1,473	)		(4,802	)		(3,365	)
Deferred		(103,202	)		(41,185	)		(330,346	)
Total income tax benefit:	$	(104,675	)	$	(45,987	)	$	(333,711	)

Loss before income taxes for the U.S. for years ended December 31, 2019, 2018, and 2017 are $499.9 million, $343.1 million, and $312.9 million, respectively. Loss before income taxes for non-U.S. jurisdictions for years ended December 31, 2019, 2018, and 2017 are $30.5 million, $24.3 million, and $14.9 million, respectively. The difference between the statutory federal income tax rate and the effective income tax rate for the years ended December 31, 2019, 2018 and 2017 is summarized as follows:

	2019			2018			2017
Statutory tax rate		21.0	%		21.0	%		35.0	%
State income taxes - net of the federal income tax benefit		1.7			1.2			1.9
Goodwill impairment		(0.7	)		(6.9	)		—
Permanent differences		(0.5	)		(0.6	)		(1.3	)
Tax effects of tax reform		—			(1.3	)		66.7
Share-based payments		(0.7	)		(0.1	)		3.6
Acquisition related differences		—			—			(3.3	)
Valuation allowance		(0.8	)		(3.7	)		—
State deferred tax remeasurement		(1.1	)		2.3			—
Other differences, net		0.8			0.6			(0.8	)
Effective tax rate		19.7	%		12.5	%		101.8	%

The effective tax rate increased by approximately 7.2% to 19.7% for 2019 compared to 12.5% for 2018. This difference was primarily due to higher goodwill impairment charges in 2018 relative to 2019, which are not deductible for tax purposes. These charges resulted in a 6.9% decrease to the effective tax rate in 2018, as compared to a 0.7% decrease to the effective tax rate in 2019. Another factor was valuation allowances being established against deferred tax assets in certain state and non-U.S. jurisdictions, which

were higher in 2018 as compared to 2019. These resulted in a 3.7% decrease to the effective tax rate in 2018, as compared to a 0.8% decrease to the rate in 2019.

The Company continues to monitor income tax developments in the United States and other countries affecting the Company. In December 2017, the United States enacted U.S. Tax Reform, which materially impacted the consolidated financial statements by decreasing the U.S. corporate statutory tax rate and significantly affecting future periods. The Company expects several proposed U.S. Treasury regulations under U.S. Tax Reform that were issued during 2018 and 2019 to be finalized during 2020. The Company will incorporate into its future financial statements the impacts, if any, of these regulations and additional authoritative guidance when finalized.

The Company continues to elect permanent reinvestment of unremitted earnings in Canada effective January 1, 2010, and it intends to do so for the foreseeable future. If the Company were to repatriate earnings, in the form of dividends or otherwise, it might be subject to certain income taxes (subject to an adjustment for foreign tax credits) and withholding taxes payable.

The tax effect of significant temporary differences representing deferred tax assets and liabilities at December 31, 2019 and 2018 are as follows (in thousands):

	2019			2018
Deferred tax assets:
Net operating loss carryforwards	$	375,308		$	324,389
Tax credits		4,138			6,404
Expense associated with stock options and restricted stock		10,561			13,375
Workers' compensation allowance		19,536			19,900
Other deferred tax asset		21,698			22,423
		431,241			386,491
Less:
Valuation allowance		(17,231	)		(13,232	)
Total deferred tax assets		414,010			373,259
Deferred tax liabilities:
Property and equipment basis difference		(607,785	)		(669,196	)
Other		(9,184	)		(10,224	)
Total deferred tax liabilities		(616,969	)		(679,420	)
Net deferred tax liability	$	(202,959	)	$	(306,161	)

In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized, and necessary allowances are provided. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. The Company considers carryback availability, the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies in making this assessment. In 2019, the Company recorded an additional $4 million of valuation allowances against its net deferred tax assets, primarily relating to certain Canadian subsidiaries. These valuation allowances were recorded due to a change in judgment as to the realizability of these assets in future tax years.

For income tax purposes, the Company has approximately $1.4 billion of gross federal net operating losses, approximately $47.4 million of gross Canadian net operating losses and approximately $847 million of post-apportionment state net operating losses as of December 31, 2019, before valuation allowances. The majority of federal net operating losses will expire in varying amounts, if unused, between 2034 and 2037. Federal net operating losses generated in 2018 and 2019 can be carried forward indefinitely. Canadian net operating losses will expire in varying amounts, if unused, between 2036 and 2039. State net operating losses will expire in varying amounts, if unused, between 2023 and 2039.

As of December 31, 2019, the Company had no unrecognized tax benefits. The Company has established a policy to account for interest and penalties related to uncertain income tax positions as operating expenses. As of December 31, 2019, the tax years ended December 31, 2014 through December 31, 2018 are open for examination by U.S. taxing authorities. As of December 31, 2019, the tax years ended December 31, 2012 through December 31, 2018 are open for examination by Canadian taxing authorities.