Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Abstract]

Components of Tax Expense (benefit) on Income From Continuing Operations

The components of the Corporation’s tax expense (benefit) on income from continuing operations are as follows:

years ended December 31 (add 000)	2015			2014			2013
Federal income taxes:
Current	$	20,627		$	35,313		$	30,856
Deferred		85,295			46,616			8,399
Total federal income taxes		105,922			81,929			39,255
State income taxes:
Current		18,153			10,307			3,201
Deferred		930			3,376			478
Total state income taxes		19,083			13,683			3,679
Foreign income taxes:
Current		99			1,262			972
Deferred		(241	)		(2,027	)		139
Total foreign income taxes		(142	)		(765	)		1,111
Total taxes on income	$	124,863		$	94,847		$	44,045

Summary of Effective Income Tax Rate on Continuing Operations

The Corporation’s effective income tax rate on continuing operations varied from the statutory United States income tax rate because of the following permanent tax differences:

years ended December 31	2015			2014			2013
Statutory tax rate		35.0	%		35.0	%		35.0	%
(Reduction) increase resulting from:
Effect of statutory depletion		(7.8	)		(9.6	)		(12.0	)
State income taxes		3.0			3.6			1.5
Domestic production deduction		(0.1	)		(0.9	)		(2.1	)
Transfer pricing		—			(0.2	)		0.9
Goodwill write off		0.4			3.9			—
Foreign tax rate differential		—			1.3			2.1
Disallowed compensation		0.2			3.7			0.3
Purchase accounting transaction costs		—			2.4			—
Other items		(0.5	)		(1.1	)		1.1
Effective income tax rate		30.2	%		38.1	%		26.8	%

Deferred Tax Assets and Liabilities

The principal components of the Corporation’s deferred tax assets and liabilities are as follows:

December 31	Deferred Assets (Liabilities)
(add 000)	2015			2014
Deferred tax assets related to:
Employee benefits	$	56,302		$	74,288
Inventories		75,907			64,484
Valuation and other reserves		42,857			48,278
Net operating loss carryforwards		11,448			171,781
Accumulated other comprehensive loss		67,757			70,367
Alternative Minimum Tax credit carryforward		48,197			28,809
Gross deferred tax assets		302,468			458,007
Valuation allowance on deferred tax assets		(8,967	)		(6,133	)
Total net deferred tax assets		293,501			451,874
Deferred tax liabilities related to:
Property, plant and equipment		(593,767	)		(638,730	)
Goodwill and other intangibles		(266,436	)		(288,471	)
Other items, net		(16,757	)		(14,618	)
Total deferred tax liabilities		(876,960	)		(941,819	)
Net deferred tax liability	$	(583,459	)	$	(489,945	)

Schedule Of Unrecognized Tax Benefits

The following table summarizes the Corporation’s unrecognized tax benefits, excluding interest and correlative effects:

years ended December 31 (add 000)	2015			2014			2013
Unrecognized tax benefits at beginning of year	$	21,107		$	11,826		$	15,380
Gross increases – tax positions in prior years		3,079			2,075			9,845
Gross decreases – tax positions in prior years		(3,512	)		(203	)		(5,121	)
Gross increases – tax positions in current year		4,978			3,369			2,540
Gross decreases – tax positions in current year		(594	)		(51	)		(529	)
Settlements with taxing authorities		—			—			(8,599	)
Lapse of statute of limitations		(6,331	)		(1,872	)		(1,690	)
Unrecognized tax benefits assumed with acquisition		—			5,963			—
Unrecognized tax benefits at end of year	$	18,727		$	21,107		$	11,826