INCOME TAXES, Effective Income Tax Reconciliation (Details)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Effective income tax rate reconciliation (as a percent):
Provision calculated at statutory rate	35.00%		21.00%	21.00%	24.50%
Impact of Tax Act			0.00%	0.10%	8.10%
State income tax, net of federal benefit			3.60%	3.60%	3.90%
Excess tax benefits related to share-based compensation			(0.60%)	(0.40%)	(0.90%)
Gains on company-owned life insurance policies which are not subject to tax			(1.00%)	(0.10%)	(0.70%)
Federal tax credits			(1.10%)	(0.90%)	(0.70%)
Other, net			0.30%	1.50%	0.60%
Total provision for income tax			22.20%	24.80%	34.80%
U.S. blended federal statutory tax rate		21.00%