Income Taxes (Tables)

12 Months Ended

Dec. 31, 2012

Income Tax Disclosure [Abstract]

Schedule of income tax expense (benefit)

The components of income before income taxes and provision for income taxes for the years ended December 31 are as follows:

	2012			2011			2010
Income before income taxes
Domestic	$	53.1		$	107.0		$	59.6
Foreign	4.9			5.3			3.1
	$	58.0		$	112.3		$	62.7
Income tax provision
Current tax provision (benefit):
Federal	$	(1.8	)	$	28.7		$	3.9
State	1.5			2.5			1.4
Foreign	1.5			1.7			0.7
Total current	1.2			32.9			6.0
Deferred tax provision (benefit):
Federal	14.1			(0.2		)	9.3
State	0.6			0.3			0.3
Foreign	(0.1		)	(0.2		)	—
Total deferred	14.6			(0.1		)	9.6
	$	15.8		$	32.8		$	15.6

Effective income tax rate reconciliation

A reconciliation of the federal statutory and effective income tax rate for the years ended December 31 is as follows:

	2012			2011			2010
Income before income taxes	$	58.0		$	112.3		$	62.7
Statutory taxes at 35.0%	$	20.3		$	39.3		$	21.9
State income taxes	1.6			1.9			1.2
Non-deductible expenses	1.1			1.3			1.2
Unremitted foreign earnings	0.1			0.1			—
Foreign statutory rate differences	(0.3		)	(1.2		)	(0.4		)
Valuation allowance	—			—			0.1
Percentage depletion	(5.0		)	(6.9		)	(7.2		)
R&D and other federal credits	(0.1		)	(0.2		)	(0.1		)
Tax controversy resolution	(0.4		)	(0.1		)	(1.1		)
Domestic production deduction	(0.7		)	—			—
Other	(0.8		)	(1.4		)	—
Income tax provision	$	15.8		$	32.8		$	15.6
Effective income tax rate	27.2		%	29.2		%	24.9		%

Deferred tax assets and liabilities

A detailed summary of the total deferred tax assets and liabilities in the Company's Consolidated Balance Sheets resulting from differences in the book and tax basis of assets and liabilities follows:

	December 31
	2012			2011
Deferred tax assets
Tax carryforwards	$	7.0		$	12.4
Inventories	3.1			4.0
Accrued expenses and reserves	24.0			23.3
Accrued pension benefits	7.4			9.9
Other employee benefits	8.0			5.8
Other	7.2			7.0
Total deferred tax assets	56.7			62.4
Less: Valuation allowance	3.1			3.0
	53.6			59.4
Deferred tax liabilities
Depreciation and depletion	45.0			35.8
Partnership investment - development costs	19.9			18.7
Unremitted foreign earnings	0.1			0.1
Total deferred tax liabilities	65.0			54.6
Net deferred tax asset (liability)	$	(11.4	)	$	4.8

Summary of tax credit carryforwards

The following table summarizes the tax carryforwards and associated carryforward periods and related valuation allowances where the Company has determined that realization is uncertain:

	December 31, 2012
	Net deferred tax asset		Valuation allowance		Carryforwards expire during:
Non-U.S. net operating loss	$	0.4	$	0.4	2019 - 2022
State losses	4.7		2.7		2013 - 2032
Alternative minimum tax credit	1.9		—		Indefinite
Total	$	7.0	$	3.1

	December 31, 2011
	Net deferred tax asset		Valuation allowance		Carryforwards expire during:
Non-U.S. net operating loss	$	0.4	$	0.4	2019 - 2022
State losses	4.9		2.6		2012-2031
Alternative minimum tax credit	5.0		—		Indefinite
Foreign tax credit	2.1		—		2019-2020
Total	$	12.4	$	3.0

Unrecognized tax benefits roll forward

	2012			2011
Balance at January 1	$	3.0		$	3.3
Additions based on tax positions related to the current year	0.2			0.1
Reductions due to settlements with taxing authorities and the lapse of the applicable statute of limitations	(0.5		)	(0.4		)
Balance at December 31	$	2.7		$	3.0