POST EMPLOYMENT BENEFITS - Fair value of total plan assets by asset category (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Fair value of total plan assets by asset category
Total	$ 18,687	$ 15,993	$ 14,385
Cash
Fair value of total plan assets by asset category
Total	432	431
Investment grade corporate bonds
Fair value of total plan assets by asset category
Total	9,300	14,184
Government bonds
Fair value of total plan assets by asset category
Total	7,360
Multi-asset fund
Fair value of total plan assets by asset category
Total	1,595	1,378
Level 1
Fair value of total plan assets by asset category
Total	432	431
Level 1 | Cash
Fair value of total plan assets by asset category
Total	432	431
Level 1 | Investment grade corporate bonds
Fair value of total plan assets by asset category
Total	0	0
Level 1 | Government bonds
Fair value of total plan assets by asset category
Total	0
Level 1 | Multi-asset fund
Fair value of total plan assets by asset category
Total	0	0
Level 2
Fair value of total plan assets by asset category
Total	18,255	15,562
Level 2 | Cash
Fair value of total plan assets by asset category
Total	0	0
Level 2 | Investment grade corporate bonds
Fair value of total plan assets by asset category
Total	9,300	14,184
Level 2 | Government bonds
Fair value of total plan assets by asset category
Total	7,360
Level 2 | Multi-asset fund
Fair value of total plan assets by asset category
Total	1,595	1,378
Level 3
Fair value of total plan assets by asset category
Total	0	0
Level 3 | Cash
Fair value of total plan assets by asset category
Total	0	0
Level 3 | Investment grade corporate bonds
Fair value of total plan assets by asset category
Total	0	0
Level 3 | Government bonds
Fair value of total plan assets by asset category
Total	0
Level 3 | Multi-asset fund
Fair value of total plan assets by asset category
Total		$ 0