EMPLOYEE BENEFIT PLANS - Components of net periodic pension expense (benefit) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Components of the net periodic pension expense (benefit)
Interest cost	$ 1,097	$ 1,014	$ 2,194	$ 2,028
Expected return on plan assets	(1,386)	(1,386)	(2,772)	(2,772)
Recognized net actuarial loss	291	460	583	921
Net pension expense	$ 2	$ 88	5	$ 177
Employer Contributions
Employer contribution			$ 0