INCOME TAXES:

The following table provides a summary of the current and deferred components of income tax expense (benefit) from continuing operations:



	Years Ended December 31,
	2018		2017			2016
Current expense (benefit):
Federal	$	30	$	(10	)	$	8
State	7		(1		)	—
Total	37		(11		)	8
Deferred expense (benefit):
Federal	$	2	$	(253	)	$	(11	)
State	10		1			(10		)
Total	12		(252		)	(21		)
Total income tax expense (benefit)	$	49	$	(263	)	$	(13	)

The differences between the Company’s effective income tax rate and the United States federal income tax statutory rate were as follows:



	Years Ended December 31,
	2018		2017			2016
Income tax expense (benefit) at federal statutory rate	$	33	$	(108	)	$	(231	)
Changes in income taxes resulting from:
Federal tax rate change	—		(249		)	—
State income taxes, net of federal income tax benefit	14		1			(6		)
Non-deductible goodwill impairment	—		92			223
Other	2		1			1
Income tax expense (benefit)	$	49	$	(263	)	$	(13	)

Deferred income taxes result from temporary differences between the financial statement carrying amounts and the tax basis of existing assets and liabilities. The table below summarizes the principal components of the Company’s deferred tax assets (liabilities) as follows:



	December 31,
	2018			2017
Deferred income tax assets:
Other postretirement benefits	$	18		$	3
Debt amortization	11			12
Other	74			65
Total deferred income tax assets	103			80
Valuation allowance	—			(2		)
Net deferred income tax assets (included within other non-current assets, net)	$	103		$	78

Deferred income tax liabilities:
Property, plant and equipment	$	(497	)	$	(484	)
Investment in unconsolidated affiliates	(2		)	(5		)
Other	(41		)	(40		)
Total deferred income tax liabilities	(540		)	(529		)
Net deferred income tax liability	$	(437	)	$	(451	)

As of December 31, 2018, the Company has $12 million ($9 million, net of federal tax) of unrecognized tax benefits, all of which would impact the Company’s effective income tax rate if recognized.

The Company’s policy is to classify and accrue interest expense and penalties on income tax underpayments (overpayments) as a component of income tax expense in its consolidated statement of operations, which is consistent with the recognition of these items in prior reporting periods.

The Company is no longer subject to examination by the Internal Revenue Service and most state jurisdictions for 2013 and prior years. However, the Company is currently under state income tax examination for its 2013 and 2014 years.

On December 22, 2017, the Tax Act was signed into law. Among other provisions, the highest corporate federal income tax rate was reduced from 35% to 21% for taxable years beginning after December 31, 2017. As a result, the Company recognized a deferred tax benefit of $249 million in December 2017.