(7) Taxes on Income

Earnings before taxes on income and details of the provision for taxes on income for the years ended December 31, 2017, 2016 and 2015 were as follows (in thousands):

	2017			2016		2015
Earnings (loss) before taxes on income:
United States	$	74,267		$	227,746	$	361,712
Foreign		(1,253	)		—		—
	$	73,014		$	227,746	$	361,712

Provision (benefit) for taxes on income:
U.S. Federal:
Current	$	11,143		$	28,919	$	64,707
Deferred		(258,703	)		49,685		59,582
	$	(247,560	)	$	78,604	$	124,289
U.S. State:
Current	$	3,861		$	4,727	$	6,280
Deferred		2,280			1,611		3,173
	$	6,141		$	6,338	$	9,453
Foreign:
Current	$	370		$	—	$	—
Deferred		160			—		—
	$	530		$	—	$	—
Consolidated:
Current	$	15,374		$	33,646	$	70,987
Deferred		(256,263	)		51,296		62,755
	$	(240,889	)	$	84,942	$	133,742

On December 22, 2017, U.S. federal tax legislation, commonly referred to as the Tax Cuts and Jobs Act (the “Act”), was signed into law with the primary provisions impacting the Company being the reduction of the U.S. corporate income tax rate from 35% to 21% and an increase in bonus tax deprecation for certain assets through 2026. As a result of the Act, the Company recognized a one-time deferred tax benefit of $269,472,000 in the 2017 fourth quarter due to the remeasurement of the Company’s U.S. deferred tax assets and liabilities based on the 21% corporate tax rate.

The Company regards these amounts as provisional amounts as they are based on reasonable estimates of temporary difference changes in 2017 and the Company’s state tax apportionment ratios. The Company expects to adjust these provisional amounts as the Company prepares its 2017 federal and state tax returns. The Company will complete its analysis of the income tax effects of the Act before the end of the measurement period on December 21, 2018.

The Company’s provision for taxes on income varied from the statutory federal income tax rate for the years ended December 31, 2017, 2016 and 2015 due to the following:

	2017			2016			2015
United States income tax statutory rate		35.0	%		35.0	%		35.0	%
State and local taxes, net of federal benefit		0.9			1.8			1.7
Change due to U.S. tax reform		(369.0	)		—			—
Other – net		3.2			0.5			0.3
		(329.9	)%		37.3	%		37.0	%

The tax effects of temporary differences that give rise to significant portions of the non-current deferred tax assets and liabilities at December 31, 2017 and 2016 were as follows (in thousands):

	2017			2016
Non-current deferred tax assets and liabilities:
Deferred tax assets:
Compensated absences	$	432		$	739
Allowance for doubtful accounts		1,875			2,534
Postretirement health care benefits		1,190			2,234
Insurance accruals		4,599			9,128
Deferred compensation		1,849			11,124
Unrealized loss on defined benefit plans		11,097			28,832
Operating loss carryforwards		15,540			7,846
Pension benefits		549			—
Other		18,474			25,735
		55,605			88,172
Valuation allowances		(15,308	)		(7,417	)
		40,297			80,755
Deferred tax liabilities:
Property		(428,947	)		(654,751	)
Deferred state taxes		(58,366	)		(54,812	)
Pension benefits		—			(2,799	)
Goodwill and other intangibles		(9,015	)		(51,551	)
Other		(12,420	)		(22,295	)
		(508,748	)		(786,208	)
	$	(468,451	)	$	(705,453	)

The Company has determined that it is more likely than not that all federal deferred tax assets at December 31, 2017 will be realized, including its operating loss carryforwards of $232,000 that expire in various amounts through 2030.

The valuation allowance for state deferred tax assets as of December 31, 2017 and 2016 was $9,289,000 and $7,417,000, respectively, related to the Company’s state net operating loss carryforwards based on the Company’s determination that it is more likely than not that the deferred tax assets will not be realized. Expiration of these state net operating loss carryforwards vary by state through 2037 and none will expire in fiscal 2018.

As of December 31, 2017, the Company had a gross Canadian net operating loss carryforward of $6,019,000 which expires in 2038. A full valuation allowance has been provided for this asset.

The Company or one of its subsidiaries files income tax returns in the United States federal jurisdiction and various state jurisdictions. The Company is currently open to audit under the statute of limitations by the Internal Revenue Service for the 2014 through 2016 tax years. With few exceptions, the Company and its subsidiaries’ state income tax returns are open to audit under the statute of limitations for the 2011 through 2016 tax years.

As of December 31, 2017, the Company has provided a liability of $2,462,000 for unrecognized tax benefits related to various income tax issues which includes interest and penalties. The amount that would impact the Company’s effective tax rate, if recognized, is $1,947,000, with the difference between the total amount of unrecognized tax benefits and the amount that would impact the effective tax rate being primarily related to the federal tax benefit of state income tax items. It is not reasonably possible to determine if the liability for unrecognized tax benefits will significantly change prior to December 31, 2018 due to the uncertainty of possible examination results.

A reconciliation of the beginning and ending amount of the liability for unrecognized tax benefits for the years ended December 31, 2017, 2016 and 2015, is as follows (in thousands):

	2017			2016			2015
Balance at beginning of year	$	2,019		$	1,958		$	1,171
Additions based on tax positions related to the current year		403			187			339
Additions for tax positions of prior years		273			867			785
Reductions for tax positions of prior years		(908	)		(441	)		(337	)
Settlements		—			(552	)		—
Balance at end of year	$	1,787		$	2,019		$	1,958

The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for federal and state income taxes. The Company recognized net expense of $120,000, $88,000 and $216,000 in interest and penalties for the years ended December 31, 2017, 2016 and 2015, respectively. The Company had $675,000, $554,000 and $522,000 of accrued liabilities for the payment of interest and penalties at December 31, 2017, 2016 and 2015, respectively.