INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Components of income tax provision

	Years ended December 31,
	2017			2016			2015
Components of Income (Loss) Before Taxes	($ in millions)
Domestic	$	53.3		$	(23.3	)	$	(66.9	)
Foreign	63.9			(10.9		)	73.6
Income (loss) before taxes	$	117.2		$	(34.2	)	$	6.7
Components of Income Tax (Benefit) Provision
Current (benefit) expense:
Federal	$	(4.0	)	$	(11.6	)	$	(16.6	)
State	3.0			0.9			1.2
Foreign	24.1			15.7			14.4
	23.1			5.0			(1.0		)
Deferred (benefit) expense:
Federal	$	(549.6	)	$	(10.1	)	$	8.9
State	14.6			(5.1		)	(2.4		)
Foreign	79.6			(20.1		)	2.6
	(455.4		)	(35.3		)	9.1
Income tax (benefit) provision	$	(432.3	)	$	(30.3	)	$	8.1

Effective tax rate reconciliation

The following table accounts for the difference between the actual tax provision and the amounts obtained by applying the statutory U.S. federal income tax rate of 35% to the income (loss) before taxes.

	Years ended December 31,
Effective Tax Rate Reconciliation (Percent)	2017		2016		2015
Statutory federal tax rate	35.0	%	35.0	%	35.0	%
State income taxes, net	(1.2	)	8.0		(38.2	)
Foreign rate differential	(7.7	)	(25.1	)	(129.8	)
U.S. tax on foreign earnings	(70.8	)	24.4		128.6
Salt depletion	(16.1	)	45.4		(38.8	)
Non-deductible transaction costs	—		—		133.1
Change in valuation allowance	76.0		(0.7	)	27.9
Remeasurement of U.S. state deferred taxes	10.2		9.4		7.6
Change in tax contingencies	(7.7	)	(9.7	)	5.0
U.S. Tax Cuts and Jobs Act	(373.5	)	—		—
Share-based payments	(5.7	)	—		—
Dividends paid to Contributing Employee Ownership Plan	(0.6	)	2.8		(11.1	)
Return to provision	(0.6	)	5.3		(4.2	)
U.S. Federal tax credits	(4.2	)	0.6		(3.1	)
Other, net	(2.0	)	(6.8	)	8.9
Effective tax rate	(368.9	)%	88.6	%	120.9	%

Components of deferred tax assets and liabilities

	December 31,
Components of Deferred Tax Assets and Liabilities	2017			2016
	($ in millions)
Deferred tax assets:
Pension and postretirement benefits	$	147.3		$	226.1
Environmental reserves	33.2			54.5
Asset retirement obligations	14.0			22.0
Accrued liabilities	37.6			53.0
Tax credits	37.1			13.2
Net operating losses	53.3			105.3
Capital loss carryforward	2.1			2.8
Other miscellaneous items	11.2			—
Total deferred tax assets	335.8			476.9
Valuation allowance	(121.4		)	(29.0		)
Net deferred tax assets	214.4			447.9
Deferred tax liabilities:
Property, plant and equipment	550.3			875.5
Intangible amortization	67.3			137.3
Inventory and prepaids	1.0			13.6
Partnerships	67.5			106.3
Taxes on unremitted earnings	3.1			223.6
Other miscellaneous items	—			4.6
Total deferred tax liabilities	689.2			1,360.9
Net deferred tax liability	$	(474.8	)	$	(913.0	)

Summary of Valuation Allowance

The activity of our deferred income tax valuation allowance was as follows:

	December 31,
	2017			2016
	($ in millions)
Beginning balance	$	29.0		$	29.3
Increases to valuation allowances	94.5			8.4
Acquisition activity	—			(4.3		)
U.S. Tax Cuts and Jobs Act	2.2			—
Decreases to valuation allowances	(5.0		)	(4.4		)
Currency translation adjustment	0.7			—
Ending balance	$	121.4		$	29.0

Unrecognized tax benefits

The amounts of unrecognized tax benefits were as follows:

	December 31,
	2017			2016
	($ in millions)
Beginning balance	$	38.4		$	35.1
Increase for current year tax positions	2.9			1.7
Increase for prior year tax positions	5.4			5.8
Reductions due to statute of limitations	(0.1		)	(0.3		)
Decrease for prior year tax positions	(9.2		)	(1.8		)
Decrease due to tax settlements	(1.1		)	(2.1		)
Ending balance	$	36.3		$	38.4

In May 2017, we reached an agreement in principle with the IRS regarding their examination of our U.S. income tax returns for 2008 and 2010 to 2012. The settlement resulted in a reduction of income tax expense of $9.5 million related primarily to favorable adjustments in uncertain tax positions for prior tax years.

Tax years subject to examination

For our primary tax jurisdictions, the tax years that remain subject to examination are as follows:

	Tax Years
U.S. federal income tax	2013 - 2016
U.S. state income tax	2006 - 2016
Canadian federal income tax	2012 - 2016
Brazil	2014 - 2016
Germany	2015 - 2016
China	2014 - 2016
The Netherlands	2014 - 2016