ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Payables and Accruals [Abstract]
Accrued compensation	$ 46,465	$ 33,809
Income taxes payable	16,216	15,725
Dividends payable	13,669	12,953
Interest rate swap liability	11,992	5,351
Contract liabilities (current)	8,501	5,008
Current portion of operating lease liability	6,513	0
Taxes, other than income taxes	5,044	6,281
Goods and services received, not yet invoiced	3,957	3,075
Accrued interest	29	3,739
KMG - Bernuth warehouse fire-related (See Note 20)	0	7,998
Other	9,056	9,679
Total	$ 121,442	$ 103,618