LOANS AND LEASES, NET - Nonaccrual (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Sep. 30, 2020
Financing Receivable, Nonaccrual [Line Items]
Loans and leases	$ 3,496,670	$ 3,322,765
Nonaccrual Loans
Financing Receivable, Nonaccrual [Line Items]
2021	20
2020	3,054
2019	9,202
2018	21,300
2017	756
Prior	2,756
Revolving Loans and Leases	0
Loans and leases	37,088
Nonaccrual With No ACL	10,896
Nonaccrual Loans \| National Lending
Financing Receivable, Nonaccrual [Line Items]
2021	20
2020	2,754
2019	8,394
2018	3,141
2017	756
Prior	2,250
Revolving Loans and Leases	0
Loans and leases	17,315
Nonaccrual With No ACL	9,019
Nonaccrual Loans \| National Lending \| Term lending
Financing Receivable, Nonaccrual [Line Items]
2021	20
2020	2,506
2019	6,862
2018	2,865
2017	147
Prior	2,070
Revolving Loans and Leases	0
Loans and leases	14,470
Nonaccrual With No ACL	7,558
Nonaccrual Loans \| National Lending \| Asset based lending
Financing Receivable, Nonaccrual [Line Items]
2021	0
2020	0
2019	0
2018	0
2017	0
Prior	0
Revolving Loans and Leases	0
Loans and leases	0
Nonaccrual With No ACL	0
Nonaccrual Loans \| National Lending \| Factoring
Financing Receivable, Nonaccrual [Line Items]
2021	0
2020	0
2019	13
2018	0
2017	0
Prior	24
Revolving Loans and Leases	0
Loans and leases	37
Nonaccrual With No ACL	37
Nonaccrual Loans \| National Lending \| Lease financing
Financing Receivable, Nonaccrual [Line Items]
2021
2020	248
2019	1,519
2018	276
2017	9
Prior	156
Revolving Loans and Leases	0
Loans and leases	2,208
Nonaccrual With No ACL	824
Nonaccrual Loans \| National Lending \| SBA/USDA
Financing Receivable, Nonaccrual [Line Items]
2021
2020
2019
2018
2017	600
Prior	0
Revolving Loans and Leases	0
Loans and leases	600
Nonaccrual With No ACL	600
Nonaccrual Loans \| National Lending \| Commercial finance
Financing Receivable, Nonaccrual [Line Items]
2021	20
2020	2,754
2019	8,394
2018	3,141
2017	756
Prior	2,250
Revolving Loans and Leases	0
Loans and leases	17,315
Nonaccrual With No ACL	9,019
Nonaccrual Loans \| Community Banking
Financing Receivable, Nonaccrual [Line Items]
2021	0
2020	300
2019	808
2018	18,159
2017	0
Prior	506
Revolving Loans and Leases	0
Loans and leases	19,773
Nonaccrual With No ACL	1,877
Nonaccrual Loans \| Community Banking \| Commercial real estate and operating
Financing Receivable, Nonaccrual [Line Items]
2021	0
2020	300
2019	700
2018	16,896
2017	0
Prior	0
Revolving Loans and Leases	0
Loans and leases	17,896
Nonaccrual With No ACL	0
Nonaccrual Loans \| Community Banking \| Consumer one-to-four family real estate and other
Financing Receivable, Nonaccrual [Line Items]
2021	0
2020	0
2019	108
2018	0
2017	0
Prior	0
Revolving Loans and Leases	0
Loans and leases	108
Nonaccrual With No ACL	108
Nonaccrual Loans \| Community Banking \| Agricultural real estate and operating
Financing Receivable, Nonaccrual [Line Items]
2021	0
2020	0
2019	0
2018	1,263
2017	0
Prior	506
Revolving Loans and Leases	0
Loans and leases	1,769
Nonaccrual With No ACL	1,769
90 or More Days Delinquent and Accruing
Financing Receivable, Nonaccrual [Line Items]
2021	2,267
2020	1,216
2019	259
2018	568
2017	40
Prior	383
Revolving Loans and Leases	0
Loans and leases	4,733
90 or More Days Delinquent and Accruing \| National Lending
Financing Receivable, Nonaccrual [Line Items]
2021	2,267
2020	1,216
2019	259
2018	568
2017	40
Prior	383
Revolving Loans and Leases	0
Loans and leases	4,733
90 or More Days Delinquent and Accruing \| National Lending \| Term lending
Financing Receivable, Nonaccrual [Line Items]
2021	1,142
2020	685
2019	36
2018	196
2017	14
Prior	0
Revolving Loans and Leases	0
Loans and leases	2,073
90 or More Days Delinquent and Accruing \| National Lending \| Lease financing
Financing Receivable, Nonaccrual [Line Items]
2021	356
2020	426
2019	223
2018	372
2017	26
Prior	0
Revolving Loans and Leases	0
Loans and leases	1,403
90 or More Days Delinquent and Accruing \| National Lending \| Insurance premium finance
Financing Receivable, Nonaccrual [Line Items]
2021	769
2020	105
2019	0
2018	0
2017	0
Prior	0
Revolving Loans and Leases	0
Loans and leases	874
90 or More Days Delinquent and Accruing \| National Lending \| Commercial finance
Financing Receivable, Nonaccrual [Line Items]
2021	2,267
2020	1,216
2019	259
2018	568
2017	40
Prior	0
Revolving Loans and Leases	0
Loans and leases	4,350
90 or More Days Delinquent and Accruing \| National Lending \| Other consumer finance
Financing Receivable, Nonaccrual [Line Items]
2021	0
2020	0
2019	0
2018	0
2017	0
Prior	383
Revolving Loans and Leases	0
Loans and leases	383
90 or More Days Delinquent and Accruing \| National Lending \| Consumer finance
Financing Receivable, Nonaccrual [Line Items]
2021	0
2020	0
2019	0
2018	0
2017	0
Prior	383
Revolving Loans and Leases	0
Loans and leases	$ 383

Amount excluding accrued interest, before allowance for credit loss, of financing receivable.

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