ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Payables and Accruals [Abstract]
Accrued compensation	$ 33,833	$ 33,809
Income taxes payable	16,470	15,725
Dividends payable	13,510	12,953
Interest rate swap liability	12,410	5,351
Contract liabilities (current)	7,293	5,008
Current portion of operating lease liability	5,498
Taxes, other than income taxes	5,330	6,281
Goods and services received, not yet invoiced	3,950	3,075
KMG - Bernuth warehouse fire-related (See Note 13)	0	7,998
Accrued interest	0	3,739
Other	11,095	9,679
Total	$ 109,389	$ 103,618