FAIR VALUES OF FINANCIAL INSTRUMENTS - Quantitative Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Range of estimated selling cost (in hundredths)	4.00%
Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Range of estimated selling cost (in hundredths)	30.00%
Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Impaired Loans, Net	$ 3,622,597	$ 2,927,755
Impaired Loans | Level 3 | Valuation, Market Approach
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Impaired Loans, Net	8,707	4,825
Foreclosed Assets | Level 3 | Valuation, Market Approach
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Impaired Loans, Net	$ 29,494	$ 31,638