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. Significant components of the Company’s deferred tax assets and liabilities as of December 31 are as follows:

	2018			2017
Deferred tax assets:
Employee benefits	$	829		$	836
Inventories		3,902			2,309
Natural gas derivatives		—			610
Goodwill & other intangibles		2,350			3,179
Net operating loss		88,341			59,536
Foreign tax credits		667			667
Interest		2,200			552
Accrued expenses		3,496			—
Other		352			1,477
Total deferred tax assets		102,137			69,166
Deferred tax liabilities:
Depreciation		30,054			14,332
Indefinite-lived intangibles		817			209
Foreign		—			26
Total deferred tax liabilities		30,871			14,567
Valuation Allowance		72,380			54,829
Net deferred tax liabilities	$	(1,114	)	$	(230	)

Significant components of the provision for income taxes for the years ended December 31 are as follows:

	2018			2017
Current:
Federal	$	—		$	(375	)
State		(34	)		(99	)
Foreign		42			581
Total current		8			107
Deferred		884			(2,134	)
	$	892		$	(2,027	)

The reconciliation of income taxes computed at the U.S. statutory tax rate to the Company’s income tax expense for the years ended December 31 is as follows:

	2018						2017
	Amount			Percent			Amount			Percent
U.S. statutory rate	$	(15,658	)		(21.0	)%	$	(89,300	)		(35.0	)%
State income taxes, net of federal tax benefit		(2,152	)		(2.9	)		(5,684	)		(2.2	)
Mining depletion		(163	)		(0.2	)		(619	)		(0.2	)
Change in election for foreign tax credits		32			—			(667	)		(0.3	)
Foreign investments		271			0.4			8,569			3.4
Stock compensation excess tax deficiency		348			0.5			876			0.3
Other permanent differences		663			0.9			1,806			0.7
Tax reform deferred rate change		—			—			28,163			11.0
Valuation allowance		17,551			23.5			54,829			21.5
	$	892			1.2	%	$	(2,027	)		(0.8	)%

As a result of the significant decline in oil and gas activities and net losses incurred over the past few years, the Company determined during the year ended December 31, 2017 that it was more likely than not that a portion of its deferred tax assets will not be realized in the future. Accordingly, the Company established a $72,380 valuation allowance against its deferred tax assets as of December 31, 2018. The Company’s assessment of the realizability of its deferred tax assets is based on the weight of all available evidence, both positive and negative, including future reversals of deferred tax liabilities.

In December 2017, the Tax Cuts and Jobs Act (“Tax Legislation”) was enacted. The Tax Legislation significantly revises the U.S. corporate income tax by, among other things, lowering corporate income tax rates, implementing the territorial tax system and imposing a repatriation tax on deemed repatriated earnings of foreign subsidiaries. In accordance with the Tax Legislation, the Company recorded $28,163 as additional income tax expense in the fourth quarter of 2017 related to the re-measurement of deferred tax assets and liabilities. Additionally, Staff Accounting Bulletin No. 118 ("SAB 118") was issued to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Act. December 22, 2018 marked the end of the measurement period for purposes of SAB 118. As such, the Company has completed the analysis based on legislative updates relating to the Tax Legislation. No material changes to the provisional amounts recorded as of December 31, 2017 were identified.

While the Tax Legislation provides for a territorial tax system, beginning in 2018, it includes the global intangible low-taxed income (“GILTI”) provision. The GILTI provisions require the Company to include in its U.S. income tax return foreign subsidiary earnings in excess of an allowable return on the foreign subsidiary’s tangible assets. FASB guidance indicates that accounting for GILTI either as part of deferred taxes or as a period cost are both acceptable methods. As of December 31, 2018, the Company has not recognized foreign earnings subject to GILTI. An accounting policy will be elected in the first period in which the GILTI provision becomes applicable to the Company.

During the years ended December 31, 2018 and 2017, the Company did not recognize benefits on foreign investments due to the uncertainty of the Company being able to realize the foreign tax assets in light of current market conditions in China and Russia. This treatment decreased income tax benefit by $271 and $8,569 for the years ended December 31, 2018 and 2017, respectively.

During 2015 through 2018, the Company incurred net operating losses in the United States. Net operating losses associated with the 2015 tax return have been carried back in full, while certain of the net operating losses incurred in 2016, 2017, and 2018 are carried forward to offset future taxable income. The cumulative recorded tax benefit of these net operating loss carryforwards totals $88,341 and $59,536 as of December 31, 2018 and 2017, respectively, and is included in the deferred income tax asset on those respective dates. Theses recorded tax benefits include the impact of the change in corporate income tax rate following the enactment of the Tax Legislation. After finalization of the 2015 Federal return and a change in the attribute of the NOL carryback, additional refunds for 2012 through 2014 tax years are being claimed in the amount of $2,107. These amounts are included within income tax receivable as of December 31, 2018 and 2017. The federal NOLs generated in 2017 and 2016 will be carried forward until they are utilized or their expiration in 2037 and 2036, respectively. The federal NOLs generated in 2018 will be carried forward until they are utilized as they do not expire per the Tax Cuts and Jobs Act. The Company has not recognized any uncertain tax positions as of December 31, 2018.

The Company files its tax returns as prescribed by the tax laws of the jurisdictions in which it operates, the most significant of which are U.S. federal and certain state jurisdictions. In 2016, the Company received an audit notice from the Internal Revenue Service for periods 2013-2015. The Company does not anticipate any material findings. The 2016 federal tax year is also subject to examination. Various U.S. state jurisdiction tax years remain open to examination as well, although the Company believes assessments, if any, would be immaterial to its consolidated financial statements.