Income Taxes

On December 22, 2017, the U.S. enacted tax legislation referred to as the Tax Cuts and Jobs Act (the "Tax Act") which significantly changes U.S. corporate income tax laws beginning, generally, in 2018. These changes include, among others, (i) a permanent reduction of the U.S. corporate income tax rate from a top marginal rate of 35% to a flat rate of 21%, (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% of adjusted taxable income, (v) limitation of the deduction for net operating losses to 80% 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. Overall, the Company expects the provisions of the Tax Act to favorably impact its future effective tax rate, after-tax earnings, and cash flows.

Income tax benefit is summarized as follows:



	Year Ended December 31,
(In thousands)	2017			2016			2015
Current
Federal	$	(9,531	)	$	(9,920	)	$	983
State	1,816			(1,848		)	(1,397		)
	(7,715		)	(11,768		)	(414		)
Deferred
Federal	(313,938		)	(218,357		)	(72,869		)
State	(7,175		)	(12,350		)	(99		)
	(321,113		)	(230,707		)	(72,968		)
Income tax benefit	$	(328,828	)	$	(242,475	)	$	(73,382	)

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



	Year Ended December 31,
	2017					2016					2015
(In thousands, except rates)	Amount			Rate		Amount			Rate		Amount			Rate
Computed "expected" federal income tax	$	(79,952	)	35.00	%	$	(230,860	)	35.00	%	$	(65,546	)	35.00	%
State income tax, net of federal income tax benefit	(4,239		)	1.86	%	(10,888		)	1.65	%	(3,152		)	1.68	%
Deferred tax adjustment related to change in overall state tax rate	(48		)	0.02	%	(663		)	0.10	%	2,822			(1.51	)%
Valuation allowance	(505		)	0.22	%	221			(0.03	)%	187			(0.10	)%
Provision to return adjustments	(3,242		)	1.42	%	(121		)	0.02	%	(6,326		)	3.38	%
Excess stock compensation	2,965			(1.30	)%	—			—	%	—			—	%
Tax Act	(242,875		)	106.32	%	—			—	%	—			—	%
Other, net	(932		)	0.41	%	(164		)	0.02	%	(1,367		)	0.73	%
Income tax benefit	$	(328,828	)	143.95	%	$	(242,475	)	36.76	%	$	(73,382	)	39.18	%

In 2017, the Company's overall effective tax rate significantly increased compared to 2016, primarily due to the Tax Act. As a result of the enactment of the Tax Act, we recorded an income tax benefit in December 2017 of $242.9 million resulting from the remeasurement of our net deferred tax liabilities based on the new lower corporate income tax rate. Although the $242.9 million tax benefit represents what we believe is a reasonable estimate of the impact of the income tax effects of the Tax Act on our Consolidated Financial Statements as of December 31, 2017, it should be considered provisional. Once we finalize certain positions when we file our 2017 tax returns, we will be able to conclude whether any further adjustments are required to our net deferred tax liability balance. Any adjustments to this provisional amount will be reported in the period in which any such adjustments are determined.

Excluding the impact of the Tax Act, the effective tax rate for 2017 was 37.6%. The effective tax rate was higher in 2015 than in 2016 and 2017 (excluding the impact of the Tax Act), primarily due to larger provision-to-return adjustments in 2015 compared to 2016 and 2017.

The composition of net deferred tax liabilities is as follows:



	December 31,
(In thousands)	2017			2016
Deferred Tax Assets
Net operating losses	$	207,633		$	352,001
Alternative minimum tax credits	208,624			218,773
Foreign tax credits	3,541			3,816
Other business credits	3,524			—
Derivative instruments	6,645			13,771
Incentive compensation	15,898			22,852
Deferred compensation	6,065			8,217
Post-retirement benefits	7,265			13,865
Equity method investments	21,812			—
Other	492			2,743
Less: valuation allowance	(16,711		)	(5,186		)
Total	464,788			630,852
Deferred Tax Liabilities
Properties and equipment	691,818			1,207,545
Equity method investments	—			2,754
Total	691,818			1,210,299
Net deferred tax liabilities	$	227,030		$	579,447

As of December 31, 2017, the Company had alternative minimum tax ("AMT") credit carryforwards of $208.6 million, which do not expire and can be used to offset regular income taxes in future years. Under the new Tax Act, the Company may claim a refund of 50% of the 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 recorded a valuation allowance in December 2017 of $10.7 million to account for the sequestration reduction the Internal Revenue Service will apply to the refundable portion of the AMT credits.

As of December 31, 2017, the Company had gross federal net operating loss ("NOL") carryforwards of $839.3 million, which will not begin to expire until 2032. The Company also had gross state NOL carryforwards of $543.7 million, the majority of which will not expire until 2023 through 2037. The Company had $5.0 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

The Company has unrecognized tax benefits of $0.7 million related to the allocation of certain gains associated with its divestitures for purposes of computing state income taxes. There was no change to the Company's unrecognized tax benefits during 2017, 2016 or 2015. If recognized, the net tax benefit of $0.7 million would not have a material effect 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 not currently under examination by the Internal Revenue Service. 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.