Statements of Consolidated Comprehensive Loss (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Consolidated net loss	$ (172.6)us-gaap_ProfitLoss	$ (85.8)us-gaap_ProfitLoss	$ (45.8)us-gaap_ProfitLoss
Foreign currency translation adjustments	(81.7)	25.0	20.7
Reclassification of hedging activities into earnings, net of tax	0.2	0.2	(1.9)
Unrealized (loss) gain on cash flow hedges, net of tax	0	(0.3)	5.9
Pension and post-retirement obligation, net of tax	(31.1)	17.9	(19.3)
Net change in accumulated other comprehensive income (loss)	(112.6)	42.8	5.4
Comprehensive loss	(285.2)	(43.0)	(40.4)
Comprehensive loss attributable to noncontrolling interests	0	1.8	7.1
Comprehensive loss attributable to OM Group, Inc.	$ (285.2)us-gaap_ComprehensiveIncomeNetOfTax	$ (41.2)us-gaap_ComprehensiveIncomeNetOfTax	$ (33.3)us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount after tax of reclassification adjustment from accumulated other comprehensive income of accumulated gain (loss) realized from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's deferred hedging gain (loss).

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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