EMPLOYEE BENEFIT PLANS - Actual and weighted-average assets allocation for qualified benefit plans (Details)	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, total actual weighted average plan asset allocations	100.00%	100.00%
Target plan asset allocations	100.00%
Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, total actual weighted average plan asset allocations	1.20%	0.40%
Target plan asset allocations	0.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, total actual weighted average plan asset allocations	52.50%	48.50%
Target plan asset allocations	63.00%
Fixed Income Funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, total actual weighted average plan asset allocations	26.90%	31.90%
Target plan asset allocations	37.00%
Other Asset Categories
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, total actual weighted average plan asset allocations	19.40%	19.20%
Target plan asset allocations	0.00%