INCOME TAXES (Details 3) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets [Abstract]
Pension and postretirement benefits	$ 108.0	$ 74.6
Environmental reserves	56.5	60.2
Asset retirement obligations	22.9	25.7
Accrued liabilities	43.9	48.2
Tax credits	9.2	13.3
Federal and state net operating losses	6.6	7.2
Capital loss carryforward	4.8	3.0
Other miscellaneous items	16.5us-gaap_DeferredTaxAssetsOther	10.7us-gaap_DeferredTaxAssetsOther
Total deferred tax assets	268.4us-gaap_DeferredTaxAssetsGross	242.9us-gaap_DeferredTaxAssetsGross
Valuation allowance	16.6	13.4	21.1
Net deferred tax assets	251.8us-gaap_DeferredTaxAssetsNet	229.5us-gaap_DeferredTaxAssetsNet
Deferred tax liabilities [Abstract]
Property, plant and equipment	177.9	182.5
Intangible amortization	10.5	8.4
Deferred Tax Liabilities, Inventory	5.6	3.1
Partnerships	98.2us-gaap_DeferredTaxLiabilitiesOther	93.7us-gaap_DeferredTaxLiabilitiesOther
Total deferred tax liabilities	292.2us-gaap_DeferredTaxLiabilities	287.7us-gaap_DeferredTaxLiabilities
Net deferred tax (liability) asset	$ (40.4)us-gaap_DeferredTaxAssetsLiabilitiesNet	$ (58.2)us-gaap_DeferredTaxAssetsLiabilitiesNet

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