INCOME TAXES (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Income taxes:
Deferred tax assets related to operating loss carryforwards in foreign jurisdictions	$ 43.2
Deferred tax assets related to domestic federal net operating loss carryforwards	2.2
Deferred tax assets related to state net operating loss carryforwards	0.4
Deferred tax assets related to state credits	11.7
Valuation allowance on deferred tax assets	40.7	$ 28.3
Total gross unrecognized tax benefits	5.8	4.1	$ 4.6	$ 9.8
Unrecognized tax benefits that would impact effective tax rate, if recognized	3.3	2.7	3.9
Accrued interest and penalties related to unrecognized tax benefits	3.0	0.4	0.6
Income tax expense for interest and penalties	0.2	0.2	0.1
Income Tax Holiday [Line Items]
Impact of tax holidays	$ 4.3	$ 4.0	$ 2.9
Benefit of tax holidays on net income per share (diluted)	$ 0.07	$ 0.07	$ 0.05
Minimum [Member]
Income taxes:
Amount of reasonably possible decrease	$ 0.5
Maximum [Member]
Income taxes:
Amount of reasonably possible decrease	$ 1.5
Earliest Tax Year [Member] | Domestic Tax Authority [Member]
Income taxes:
Operating loss carryforwards, year of expiration	Jan. 01, 2019
Earliest Tax Year [Member] | State and Local Jurisdiction [Member]
Income taxes:
Operating loss carryforwards, year of expiration	Jan. 01, 2016
Tax credit carryforwards, year of expiration	Jan. 01, 2016
Latest Tax Year [Member] | Domestic Tax Authority [Member]
Income taxes:
Operating loss carryforwards, year of expiration	Dec. 31, 2033
Latest Tax Year [Member] | State and Local Jurisdiction [Member]
Income taxes:
Operating loss carryforwards, year of expiration	Dec. 31, 2033
Tax credit carryforwards, year of expiration	Dec. 31, 2026
Inland Revenue, Singapore (IRAS) [Member]
Income Tax Holiday [Line Items]
Income tax holiday, year of expiration	2016
Puerto Rico Tax Authority [Member]
Income Tax Holiday [Line Items]
Income tax holiday, year of expiration	2025