INCOME TAXES - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Income Taxes
Tax act, provisional income tax benefit		$ 68.1
Tax credit carryforward amount subject to expiration	$ 36.9
Undistributed earnings of international subsidiaries	4.4
Reserve on unrecognized tax benefits that would benefit the effective tax rate	2.2
Interest and penalties	0.1	$ 0.1	$ 0.1
Accrued interest and penalties related to unrecognized tax benefits	1.2
Expiring from 2030 to 2039
Income Taxes
Tax credit carryforward amount subject to expiration	35.7
Expiring from 2020 to 2029
Income Taxes
Tax credit carryforward amount subject to expiration	0.5
Tax Credit Carryforward, Without Expiration
Income Taxes
Tax credit carryforward amount subject to expiration	0.7
Domestic Tax Authority
Income Taxes
Operating loss carryforwards	31.4
Operating loss carryforwards, subject to expiration	13.1
Operating loss carryforwards, not subject to expiration	18.3
State and Local Jurisdiction
Income Taxes
Operating loss carryforwards	13.4
Foreign Tax Authority | Canada Revenue Agency
Income Taxes
Operating loss carryforwards	2.8
Foreign Tax Authority | Her Majesty's Revenue and Customs (HMRC)
Income Taxes
Operating loss carryforwards	$ 0.6