BUSINESS COMBINATIONS - Pro Forma Schedule (Details) - Galleria - USD ($) $ / shares in Units, shares in Millions, $ in Millions		12 Months Ended
Oct. 01, 2016	Jun. 30, 2017
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Pro forma Net revenues		$ 8,889.2
Pro forma Net (loss) income		(101.2)
Pro forma Net (loss) income attributable to Coty Inc.		$ (142.7)
Pro forma Net (loss) income attributable to Coty Inc. per common share
Basic (in dollars per share)		$ (0.19)
Diluted (in dollars per share)		$ (0.19)
Acquisition-related costs
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Pro forma Net (loss) income		$ (476.3)
Amortization of inventory step up
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Pro forma Net (loss) income		$ (89.6)
Majority Shareholders \| Pre-Merger Holders of Galleria Common Stock
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Number of shares received by former holders of Galleria common stock (in shares)	409.7

Business Acquisition, Pro Forma Earnings Per Share [Abstract]

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Number of shares of equity interests issued or issuable to acquire entity.

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The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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