Income Taxes

On December 22, 2017, the U.S. enacted the Tax Act which significantly changed U.S. corporate income tax laws beginning, generally, in 2018. These changes included, among others, (i) a permanent reduction of the U.S. corporate income tax rate from a top marginal rate of 35 percent to a flat rate of 21 percent, (ii) elimination of the corporate alternative minimum tax, (iii) immediate deductions for certain new investments instead of deductions for depreciation expense over time, (iv) limitation on the tax deduction for interest expense to 30 percent of adjusted taxable income, (v) limitation of the deduction for net operating losses to 80 percent of current year taxable income and elimination of net operating loss carrybacks, and (vi) elimination of many business deductions and credits, including the domestic production activities deduction, the deduction for entertainment expenditures, and the deduction for certain executive compensation in excess of $1 million. The 2018 tax provision reflects the legislative changes noted above, including the new corporate tax rate of 21 percent.

Income tax expense (benefit) is summarized as follows:



	Year Ended December 31,
(In thousands)	2018			2017			2016
Current
Federal	$	(95,191	)	$	(9,531	)	$	(9,920	)
State	6,682			1,816			(1,848		)
	(88,509		)	(7,715		)	(11,768		)
Deferred
Federal	230,643			(313,938		)	(218,357		)
State	(1,040		)	(7,175		)	(12,350		)
	229,603			(321,113		)	(230,707		)
Income tax expense (benefit)	$	141,094		$	(328,828	)	$	(242,475	)

Income tax expense (benefit) was different than the amounts computed by applying the statutory federal income tax rate as follows:



	Year Ended December 31,
	2018					2017					2016
(In thousands, except rates)	Amount			Rate		Amount			Rate		Amount			Rate
Computed "expected" federal income tax	$	146,609		21.00	%	$	(79,952	)	35.00	%	$	(230,860	)	35.00	%
State income tax, net of federal income tax benefit	11,850			1.70	%	(4,239		)	1.86	%	(10,888		)	1.65	%
Deferred tax adjustment related to change in overall state tax rate	(15,208		)	(2.18	)%	(48		)	0.02	%	(663		)	0.10	%
Valuation allowance	8,975			1.29	%	(505		)	0.22	%	221			(0.03	)%
Provision to return adjustments	(1,773		)	(0.25	)%	(3,242		)	1.42	%	(121		)	0.02	%
Excess stock compensation	327			0.05	%	2,965			(1.30	)%	—			—	%
Tax Act	(11,367		)	(1.63	)%	(242,875		)	106.32	%	—			—	%
Other, net	1,681			0.24	%	(932		)	0.41	%	(164		)	0.02	%
Income tax expense (benefit)	$	141,094		20.21	%	$	(328,828	)	143.95	%	$	(242,475	)	36.76	%

In 2018, the Company's overall effective tax rate significantly decreased compared to 2017, primarily due to the Tax Act. As a result of the enactment of the Tax Act, the Company recorded an income tax benefit in December 2017 of $242.9 million resulting from the remeasurement of its net deferred tax liabilities based on the new lower corporate income tax rate. The Company recorded an additional $11.4 million tax benefit in 2018 for the Tax Act, of which $10.7 million relates to the reversal of the valuation allowance for the sequestration reduction on the refundable portion of alternative minimum tax (AMT) credits, and the remainder relates to finalizing certain tax positions with the filing of the 2017 tax returns. The accounting for the income tax effects of the Tax Act has been completed and all adjustments are reflected in our Consolidated Financial Statements as of December 31, 2018.

Excluding the discrete impact of the Tax Act, the adjusted effective tax rates were 21.8 percent for 2018 and 37.6 percent for 2017. The effective tax rate was lower in 2018 than in 2017 primarily due to the reduction of the U.S. corporate income tax rate from 35 percent to 21 percent, a reduction in our estimated net state deferred tax liabilities as a result of updated state apportionment factors in the states in which the Company operates, and smaller provision-to-return adjustments in 2018 compared to 2017.

The composition of net deferred tax liabilities is as follows:



	December 31,
(In thousands)	2018			2017
Deferred Tax Assets
Net operating losses	$	56,769		$	207,633
Alternative minimum tax credits	114,149			208,624
Foreign tax credits	3,473			3,541
Other business credits	3,380			3,524
Derivative instruments	—			6,645
Incentive compensation	17,378			15,898
Deferred compensation	5,690			6,065
Post-retirement benefits	6,799			7,265
Equity method investments	20,746			21,812
Capital loss carryforward	8,877			—
Other	2,957			492
Less: valuation allowance	(14,943		)	(16,711		)
Total	225,275			464,788
Deferred Tax Liabilities
Properties and equipment	670,704			691,818
Derivative instruments	13,168			—
Total	683,872			691,818
Net deferred tax liabilities	$	458,597		$	227,030

Under the Tax Act of 2017, the Company may claim a refund of 50 percent of its 2017 remaining AMT credits (to the extent the credits exceed regular tax for the year) in 2018, 2019 and 2020. Any AMT credits remaining after 2020 will be refunded in 2021. The Company had recorded a valuation allowance in December 2017 of $10.7 million to account for the sequestration reduction the Internal Revenue Service (IRS) would apply to the refundable portion of the AMT credits. This valuation allowance was reversed in December 2018, as the IRS announced that refunds of AMT credits as provided under the 2017 Tax Act will not be subject to sequester.

As of December 31, 2018, the Company reclassified $114.1 million of its AMT credit carryforward to current income tax receivable, and has a remaining AMT credit carryforward balance of $114.1 million, which will be used to offset regular income taxes in 2019 and 2020 before being fully refunded by 2021.

As of December 31, 2018, the Company had a gross federal net operating loss (NOL) carryforward of $142.6 million, which will not begin to expire until 2036. The Company also had gross state NOL carryforwards of $468.1 million, the majority of which will not expire until 2024 through 2037. The Company had $14.1 million of state NOL valuation allowances, and believes it is more likely than not that the remainder of the deferred tax benefits associated with federal and state NOL carryforwards will be utilized prior to their expiration.

Unrecognized Tax Benefits

A reconciliation of unrecognized tax benefits is as follows:



	Year Ended December 31,
(In thousands)	2018		2017		2016
Balance at beginning of year	$	663	$	663	$	663
Additions for tax positions of prior years	16,187		—		—
Balance at end of year	$	16,850	$	663	$	663

As of December 31, 2018, the Company had a $16.9 million net reserve for unrecognized tax benefits primarily related to AMT associated with uncertain tax positions, and a $3.1 million liability for accrued interest associated with the uncertain tax positions. Any additional AMT payments could be utilized as credits against future regular tax liabilities and would be fully refunded from 2018 through 2021 under the Tax Act. Accordingly, the uncertain tax positions identified would not have a material impact on the Company's effective tax rate.

The Company files income tax returns in the U.S. federal, various states and other jurisdictions. The Company is no longer subject to examinations by state authorities before 2012 or by federal authorities before 2013. The Company is currently under examination by the Internal Revenue Service for its 2014, 2015, and 2016 tax years. The Company believes that appropriate provisions have been made for all jurisdictions and all open years, and that any assessment on these filings will not have a material impact on the Company's financial position, results of operations or cash flows.