CONDENSED CONSOLIDATED STATEMENTS OF EQUITY AND REDEEMABLE NONCONTROLLING INTERESTS - USD ($) shares in Millions, $ in Millions	Total	Preferred Stock	Common Stock Class A Common Stock	Additional Paid-in Capital	(Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Total Coty Inc. Stockholders’ Equity	Noncontrolling Interests	As Previously Reported	As Previously Reported Preferred Stock	As Previously Reported Common Stock Class A Common Stock	As Previously Reported Additional Paid-in Capital	As Previously Reported (Accumulated Deficit)	As Previously Reported Accumulated Other Comprehensive Income (Loss)	As Previously Reported Treasury Stock	As Previously Reported Total Coty Inc. Stockholders’ Equity	As Previously Reported Noncontrolling Interests	As Adjusted	As Adjusted Preferred Stock	As Adjusted Common Stock Class A Common Stock	As Adjusted Additional Paid-in Capital	As Adjusted (Accumulated Deficit)	As Adjusted Accumulated Other Comprehensive Income (Loss)	As Adjusted Treasury Stock	As Adjusted Total Coty Inc. Stockholders’ Equity	As Adjusted Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to the adoption of ASU | Accounting Standards Update 2016-09	$ 8.3				$ 8.3			$ 8.3
Balance, beginning of period (in shares) at Jun. 30, 2017		4.2	812.9				65.0				4.2	812.9				65.0
Balance, beginning of period at Jun. 30, 2017	9,326.0	$ 0.0	$ 8.1	$ 11,203.2	(450.9)	$ 4.4	$ (1,441.8)	9,323.0	$ 3.0	$ 9,317.7	$ 0.0	$ 8.1	$ 11,203.2	$ (459.2)	$ 4.4	$ (1,441.8)	$ 9,314.7	$ 3.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of employee stock options and restricted stock units (in shares)			1.5
Exercise of employee stock options and restricted stock units	11.2		$ 0.0	11.2				11.2
Shares withheld for employee taxes	(3.1)			(3.1)				(3.1)
Share-based compensation expense	8.1			8.1				8.1
Dividends ($0.125 per Common Share)	(94.3)			(94.3)				(94.3)
Net income (loss)	(21.9)				(19.7)			(19.7)	(2.2)
Other comprehensive loss	239.7					239.1		239.1	0.6
Distribution of redeemable noncontrolling interest due to additional contribution	17.0			17.0				17.0
Adjustment of redeemable noncontrolling interests to redemption value	(29.0)			(29.0)				(29.0)
Balance, end of period (in shares) at Sep. 30, 2017		4.2	814.4				65.0
Balance, end of period at Sep. 30, 2017	9,453.7	$ 0.0	$ 8.1	11,113.1	(470.6)	243.5	$ (1,441.8)	9,452.3	1.4
Balance, beginning of period at Jun. 30, 2017	551.1									551.1
Redeemable Noncontrolling Interests
Net income (loss)	5.8
Distribution to noncontrolling interests, net	(6.4)
Dilution of redeemable noncontrolling interest due to additional contribution	(17.0)
Adjustment of redeemable noncontrolling interests to redemption value	29.0
Balance, end of period at Sep. 30, 2017	562.5
Balance, beginning of period (in shares) at Jun. 30, 2017		4.2	812.9				65.0				4.2	812.9				65.0
Balance, beginning of period at Jun. 30, 2017	9,326.0	$ 0.0	$ 8.1	11,203.2	(450.9)	4.4	$ (1,441.8)	9,323.0	3.0	9,317.7	$ 0.0	$ 8.1	11,203.2	(459.2)	4.4	$ (1,441.8)	9,314.7	3.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive loss	280.0
Balance, end of period (in shares) at Dec. 31, 2017		5.2	814.8				65.0
Balance, end of period at Dec. 31, 2017	9,428.5	$ 0.0	$ 8.1	10,940.3	(361.4)	283.9	$ (1,441.8)	9,429.1	(0.6)
Balance, beginning of period at Jun. 30, 2017	551.1									551.1
Balance, end of period at Dec. 31, 2017	638.3
Balance, beginning of period (in shares) at Sep. 30, 2017		4.2	814.4				65.0
Balance, beginning of period at Sep. 30, 2017	9,453.7	$ 0.0	$ 8.1	11,113.1	(470.6)	243.5	$ (1,441.8)	9,452.3	1.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Preferred Stock (in shares)		1.0
Exercise of employee stock options and restricted stock units (in shares)			0.4
Exercise of employee stock options and restricted stock units	2.5			2.5				2.5
Shares withheld for employee taxes	(0.3)			(0.3)				(0.3)
Share-based compensation expense	9.0			9.0				9.0
Dividends ($0.125 per Common Share)	(94.4)			(94.4)				(94.4)
Net income (loss)	107.3				109.2			109.2	(1.9)
Other comprehensive loss	40.3					40.4		40.4	(0.1)
Additional redeemable noncontrolling interests due to employee grants (See Note 17)	(8.3)			(8.3)				(8.3)
Adjustment of redeemable noncontrolling interests to redemption value	(81.3)			(81.3)				(81.3)
Balance, end of period (in shares) at Dec. 31, 2017		5.2	814.8				65.0
Balance, end of period at Dec. 31, 2017	9,428.5	$ 0.0	$ 8.1	10,940.3	(361.4)	283.9	$ (1,441.8)	9,429.1	(0.6)
Balance, beginning of period at Sep. 30, 2017	562.5
Redeemable Noncontrolling Interests
Net income (loss)	11.3
Distribution to noncontrolling interests, net	(25.3)
Additional redeemable noncontrolling interests due to employee grants	8.3
Proceeds from noncontrolling interests	0.2
Adjustment of redeemable noncontrolling interests to redemption value	81.3
Balance, end of period at Dec. 31, 2017	638.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment due to the adoption of ASU | Accounting Standards Update 2016-16																			$ (112.6)				$ (112.6)			$ (112.6)
Adjustment due to the adoption of ASU | Accounting Standards Update 2014-09																			(18.2)				(18.2)			(18.2)
Balance, beginning of period (in shares) at Jun. 30, 2018											5.0	815.8				65.0				5.0	815.8				65.0
Balance, beginning of period at Jun. 30, 2018	8,855.2					158.8				8,855.2	$ 0.0	$ 8.1	10,750.8	(626.2)	158.8	$ (1,441.8)	8,849.7	5.5	8,724.4	$ 0.0	$ 8.1	$ 10,750.8	(757.0)	$ 158.8	$ (1,441.8)	8,718.9	$ 5.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of employee stock options and restricted stock units (in shares)			0.0
Exercise of employee stock options and restricted stock units	0.7		$ 0.0	0.7				0.7
Share-based compensation expense	6.4			6.4				6.4
Dividends ($0.125 per Common Share)	(94.0)			(94.0)				(94.0)
Net income (loss)	(10.9)				(12.1)			(12.1)	1.2
Other comprehensive loss	(47.8)					(48.0)		(48.0)	0.2
Distribution to noncontrolling interests, net	(1.3)								(1.3)
Additional redeemable noncontrolling interests due to employee grants (See Note 17)	(1.6)			(1.6)				(1.6)
Adjustment of redeemable noncontrolling interests to redemption value	37.2			37.2				37.2
Balance, end of period (in shares) at Sep. 30, 2018		5.0	815.8				65.0
Balance, end of period at Sep. 30, 2018	8,613.1	$ 0.0	$ 8.1	10,699.5	(769.1)	110.8	$ (1,441.8)	8,607.5	5.6
Balance, beginning of period at Jun. 30, 2018										661.3									661.3
Redeemable Noncontrolling Interests
Net income (loss)	0.8
Distribution to noncontrolling interests, net	(4.3)
Additional redeemable noncontrolling interests due to employee grants	1.6
Adjustment of redeemable noncontrolling interests to redemption value	(37.2)
Balance, end of period at Sep. 30, 2018	622.2
Balance, beginning of period (in shares) at Jun. 30, 2018											5.0	815.8				65.0				5.0	815.8				65.0
Balance, beginning of period at Jun. 30, 2018	8,855.2					158.8				8,855.2	$ 0.0	$ 8.1	$ 10,750.8	$ (626.2)	$ 158.8	$ (1,441.8)	$ 8,849.7	$ 5.5	8,724.4	$ 0.0	$ 8.1	$ 10,750.8	$ (757.0)	$ 158.8	$ (1,441.8)	$ 8,718.9	$ 5.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends ($0.125 per Common Share)				(188.4)
Other comprehensive loss	(125.0)
Additional redeemable noncontrolling interests due to employee grants (See Note 17)				(1.6)
Balance, end of period (in shares) at Dec. 31, 2018		1.9	816.2				65.0
Balance, end of period at Dec. 31, 2018	7,611.3	$ 0.0	$ 8.1	10,734.9	(1,729.7)	33.6	$ (1,441.8)	7,605.1	6.2
Balance, beginning of period at Jun. 30, 2018										$ 661.3									$ 661.3
Redeemable Noncontrolling Interests
Additional redeemable noncontrolling interests due to employee grants	1.6
Balance, end of period at Dec. 31, 2018	487.6
Balance, beginning of period (in shares) at Sep. 30, 2018		5.0	815.8				65.0
Balance, beginning of period at Sep. 30, 2018	8,613.1	$ 0.0	$ 8.1	10,699.5	(769.1)	110.8	$ (1,441.8)	8,607.5	5.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cancellation of preferred stock (in shares)		(3.1)
Stock cancelled during period, amount		$ 0.0
Exercise of employee stock options and restricted stock units (in shares)			0.4
Exercise of employee stock options and restricted stock units	0.2		$ 0.0	0.2				0.2
Shares withheld for employee taxes	(1.3)			(1.3)				(1.3)
Share-based compensation expense	4.4			4.4				4.4
Dividends ($0.125 per Common Share)	(94.6)			(94.6)				(94.6)
Net income (loss)	(960.0)				(960.6)			(960.6)	0.6
Other comprehensive loss	(77.2)					(77.2)		(77.2)
Additional redeemable noncontrolling interests due to employee grants (See Note 17)				(1.6)
Adjustment of redeemable noncontrolling interests to redemption value	126.7			126.7				126.7
Balance, end of period (in shares) at Dec. 31, 2018		1.9	816.2				65.0
Balance, end of period at Dec. 31, 2018	7,611.3	$ 0.0	$ 8.1	$ 10,734.9	$ (1,729.7)	$ 33.6	$ (1,441.8)	$ 7,605.1	$ 6.2
Balance, beginning of period at Sep. 30, 2018	622.2
Redeemable Noncontrolling Interests
Net income (loss)	4.0
Distribution to noncontrolling interests, net	(11.9)
Additional redeemable noncontrolling interests due to employee grants	1.6
Adjustment of redeemable noncontrolling interests to redemption value	(126.7)
Balance, end of period at Dec. 31, 2018	$ 487.6