Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Components of income before income taxes

The components of income before income taxes from continuing operations for each of the years ended December 31 were as follows:

	2016			2015			2014
				(In thousands)
United States	$	326,252		$	248,379		$	249,501
Foreign	(24		)	(1,326		)	(52		)
Income before income taxes from continuing operations	$	326,228		$	247,053		$	249,449

Income tax expense

Income tax expense from continuing operations for the years ended December 31 was as follows:

	2016			2015			2014
				(In thousands)
Current:
Federal	$	81,989		$	85,897		$	8,837
State	13,190			10,093			622
Foreign	2			30			—
	95,181			96,020			9,459
Deferred:
Income taxes:
Federal	(2,102		)	(19,632		)	52,041
State	1,184			(5,304		)	1,913
Investment tax credit - net	(1,131		)	(420		)	1,009
	(2,049		)	(25,356		)	54,963
Total income tax expense	$	93,132		$	70,664		$	64,422

Deferred tax assets and deferred tax liabilities

Components of deferred tax assets and deferred tax liabilities at December 31 were as follows:

	2016		2015
	(In thousands)
Deferred tax assets:
Postretirement	$	87,872	$	97,666
Compensation-related	44,995		33,714
Alternative minimum tax credit carryforward	29,338		28,169
Federal renewable energy credit	16,944		3,400
Customer advances	13,524		12,623
Legal and environmental contingencies	9,895		6,377
Asset retirement obligations	8,867		8,694
Other	46,957		43,306
Total deferred tax assets	258,392		233,949
Deferred tax liabilities:
Depreciation and basis differences on property, plant and equipment	774,838		756,444
Postretirement	70,670		71,835
Intangible asset amortization	26,413		23,950
Other	45,580		36,359
Total deferred tax liabilities	917,501		888,588
Valuation allowance	9,117		8,990
Net deferred income tax liability	$	668,226	$	663,629

Schedule of change in net deferred income tax liability reconciliation

The following table reconciles the change in the net deferred income tax liability from December 31, 2015, to December 31, 2016, to deferred income tax expense:

	2016
(In thousands)
Change in net deferred income tax liability from the preceding table	$	4,597
Deferred taxes associated with other comprehensive income	(825		)
Other	(5,821		)
Deferred income tax benefit for the period	$	(2,049	)

Reconciliation of income tax expense (benefit) at statutory federal rate versus actual rate

Total income tax expense differs from the amount computed by applying the statutory federal income tax rate to income before taxes. The reasons for this difference were as follows:

Years ended December 31,	2016					2015					2014
	Amount			%		Amount			%		Amount			%
	(Dollars in thousands)
Computed tax at federal statutory rate	$	114,179		35.0		$	86,468		35.0		$	87,308		35.0
Increases (reductions) resulting from:
State income taxes, net of federal income tax	9,027			2.8		8,208			3.3		7,019			2.8
Federal renewable energy credit	(13,544		)	(4.2	)	(3,400		)	(1.4	)	(3,655		)	(1.5	)
Tax compliance and uncertain tax positions	(3,028		)	(.9	)	(2,607		)	(1.0	)	(8,568		)	(3.4	)
Domestic production activities	(6,251		)	(1.9	)	(6,842		)	(2.8	)	(3,993		)	(1.6	)
Other	(7,251		)	(2.3	)	(11,163		)	(4.5	)	(13,689		)	(5.5	)
Total income tax expense	$	93,132		28.5		$	70,664		28.6		$	64,422		25.8

Reconciliation of unrecognized tax benefits (excluding interest)

A reconciliation of the unrecognized tax benefits (excluding interest) for the years ended December 31 was as follows:

	2016		2015			2014
			(In thousands)
Balance at beginning of year	$	—	$	105		$	7,845
Settlements	—		—			(7,740		)
Lapse of statute of limitations	—		(105		)	—
Balance at end of year	$	—	$	—		$	105