INCOME TAX EXPENSE (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
INCOME TAX EXPENSE
Effective income tax rate	14.30%		19.50%		15.90%	19.40%
Increase (decrease) in valuation allowance (as a percent)		(5.10%)	1.40%			4.30%
Reduction in valuation allowance for excess foreign tax credits		$ 2.8	$ 0.1	$ 2.3		$ 2.4
Amended return receivable			$ 0.1	$ 0.2		$ 0.3
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Percent	6.30%				2.40%
Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Percent	1.40%		1.80%		0.60%	0.60%
Effective Income Tax Rate Reconciliation, Deduction, Percent	1.10%				0.40%
Effective Income Tax Rate Reconciliation, Research Tax Credit And Adjustments For Prior Years' Tax Return To Provision True-Ups, Percent	1.60%				0.60%
Foreign tax credit	6.30%				2.40%