EMPLOYEE BENEFIT PLANS - Plan assets and benefit obligation of the defined benefit plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Change in plan assets:
Fair value of plan assets at beginning of fiscal year	$ 160,523
Fair value of plan assets at end of fiscal year	144,091	$ 160,523
Pension Plan
Change in benefit obligation:
Benefit obligation at beginning of fiscal year	170,505	183,003
Business acquisition	21,839	0
Interest cost	3,448	2,816	$ 4,267
Benefits paid	(11,281)	(10,743)
Actuarial (gain) loss	(35,490)	(4,571)
Benefit obligation at end of fiscal year	149,021	170,505	183,003
Change in plan assets:
Fair value of plan assets at beginning of fiscal year	160,523	147,145
Business acquisition	22,288	0
Actual return on plan assets	(27,439)	23,199
Company contributions	0	922
Benefits paid	(11,281)	(10,743)
Fair value of plan assets at end of fiscal year	144,091	160,523	147,145
Projected benefit obligation in excess of plan assets	(4,930)	(9,982)
Amounts recognized in the statement of financial position consist of:
Accrued liabilities	0	0
Other liabilities (long-term)	(4,930)	(9,982)
Total Liabilities	(4,930)	(9,982)
Net actuarial losses	32,176	38,296
Prior service cost	0	0
Deferred taxes	(6,757)	(8,042)
Total Accumulated other comprehensive loss, net of tax	25,419	30,254
Net amount recognized at September 30,	20,489	20,272
Accumulated benefit obligations	149,021	170,505
Information for plans with accumulated benefit obligations in excess of plan assets:
ABO	149,021	170,505
PBO	149,021	170,505
Fair value of plan assets	144,091	160,523
Supplemental Employee Retirement Plan
Change in benefit obligation:
Benefit obligation at beginning of fiscal year	14,775	16,070
Business acquisition	0	0
Interest cost	172	162	335
Benefits paid	(1,927)	(1,936)
Actuarial (gain) loss	(1,098)	479
Benefit obligation at end of fiscal year	11,922	14,775	16,070
Change in plan assets:
Fair value of plan assets at beginning of fiscal year	0	0
Business acquisition	0	0
Actual return on plan assets	0	0
Company contributions	1,927	1,936
Benefits paid	(1,927)	(1,936)
Fair value of plan assets at end of fiscal year	0	0	$ 0
Projected benefit obligation in excess of plan assets	(11,922)	(14,775)
Amounts recognized in the statement of financial position consist of:
Accrued liabilities	(1,866)	(1,884)
Other liabilities (long-term)	(10,056)	(12,891)
Total Liabilities	(11,922)	(14,775)
Net actuarial losses	6,003	7,662
Prior service cost	0	0
Deferred taxes	(1,261)	(1,609)
Total Accumulated other comprehensive loss, net of tax	4,742	6,053
Net amount recognized at September 30,	(7,180)	(8,722)
Accumulated benefit obligations	11,922	14,775
Information for plans with accumulated benefit obligations in excess of plan assets:
ABO	11,922	14,775
PBO	11,922	14,775
Fair value of plan assets	$ 0	$ 0