Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Schedule of Deferred Tax Assets and Liabilities

The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and liabilities at December 31, 2018 and 2017 are presented below (in thousands):



	December 31,
	2018			2017
Deferred tax assets:
Benefit of tax loss carryforwards	$	12,521		$	24,035
Alternative minimum tax credit carryforward	8,855			16,620
Pensions and benefits	31,874			32,606
Asset retirement obligation	21,305			19,530
Regulatory liabilities related to income taxes	63,378			63,794
Deferred fuel	2,483			1,405
Other	2,673			—
Total gross deferred tax assets	143,089			157,990
Deferred tax liabilities:
Plant, principally due to depreciation and basis differences	(437,465		)	(426,077		)
Decommissioning	(30,757		)	(34,520		)
Other	—			(2,416		)
Total gross deferred tax liabilities	(468,222		)	(463,013		)
Net accumulated deferred income taxes	$	(325,133	)	$	(305,023	)

Schedule of Components of Income Tax Expense (Benefit)

The Company recognized income tax expense for 2018, 2017 and 2016 as follows (in thousands):



	Years Ended December 31,
	2018			2017			2016
Income tax expense (benefit):
Federal:
Current	$	(4,638	)	$	2,507		$	2,642
Deferred	24,121			46,089			47,909
Total federal income tax	19,483			48,596			50,551
State:
Current	1,888			(897		)	766
Deferred	1,941			1,816			3,285
Total state income tax	3,829			919			4,051
Generation (amortization) of accumulated investment tax credits	3,056			1,489			(684		)
Total income tax expense	$	26,368		$	51,004		$	53,918

Schedule of Effective Income Tax Rate Reconciliation

Income tax provisions differ from amounts computed by applying the statutory federal income tax rate of 21% in 2018 and 35% in 2017 and 2016 to book income before federal income tax as follows (in thousands):



	Years Ended December 31,
	2018			2017			2016
Federal income tax expense computed on income at statutory rate	$	23,243		$	52,243		$	52,740
Difference due to:
State taxes, net of federal benefit	3,059			597			2,633
AEFUDC	(182		)	450			(475		)
Permanent tax differences	(682		)	(2,562		)	(2,369		)
Other	930			276			1,389
Total income tax expense	$	26,368		$	51,004		$	53,918
Effective income tax rate	23.8		%	34.2		%	35.8		%

Summary of Income Tax Contingencies

A reconciliation of the December 31, 2018, 2017 and 2016 amounts of unrecognized tax benefits are as follows (in thousands):



	2018			2017			2016
Balance at January 1	$	4,200		$	5,300		$	6,000
Additions for tax positions related to the current year	—			200			400
Reductions for tax positions related to the current year	(200		)	—			—
Additions for tax positions of prior years	700			400			100
Reductions for tax positions of prior years	—			(1,700		)	(1,200		)
Balance at December 31	$	4,700		$	4,200		$	5,300