LOANS AND LEASES, NET - Past Due Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023
Financing Receivable, Past Due [Line Items]
Loans and leases	$ 4,426,281	$ 4,366,116
Accruing and Nonaccruing Loans and Leases
Financing Receivable, Past Due [Line Items]
Loans and leases	4,488,882	4,437,460
Accruing and Nonaccruing Loans and Leases | Total loans and leases held for investment
Financing Receivable, Past Due [Line Items]
Loans and leases	4,419,364	4,359,681
Accruing and Nonaccruing Loans and Leases | National Lending | Loans held for sale
Financing Receivable, Past Due [Line Items]
Loans and leases	69,518	77,779
Accruing and Nonaccruing Loans and Leases | National Lending | Term lending
Financing Receivable, Past Due [Line Items]
Loans and leases	1,452,274	1,308,133
Accruing and Nonaccruing Loans and Leases | National Lending | Asset-based lending
Financing Receivable, Past Due [Line Items]
Loans and leases	379,681	382,371
Accruing and Nonaccruing Loans and Leases | National Lending | Factoring
Financing Receivable, Past Due [Line Items]
Loans and leases	335,953	358,344
Accruing and Nonaccruing Loans and Leases | National Lending | Lease financing
Financing Receivable, Past Due [Line Items]
Loans and leases	188,889	183,392
Accruing and Nonaccruing Loans and Leases | National Lending | Insurance premium finance
Financing Receivable, Past Due [Line Items]
Loans and leases	671,035	800,077
Accruing and Nonaccruing Loans and Leases | National Lending | SBA/USDA
Financing Receivable, Past Due [Line Items]
Loans and leases	546,048	524,750
Accruing and Nonaccruing Loans and Leases | National Lending | Other commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	160,628	166,091
Accruing and Nonaccruing Loans and Leases | National Lending | Commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	3,734,508	3,723,158
Accruing and Nonaccruing Loans and Leases | National Lending | Consumer finance
Financing Receivable, Past Due [Line Items]
Loans and leases	301,510	254,416
Accruing and Nonaccruing Loans and Leases | National Lending | Tax services
Financing Receivable, Past Due [Line Items]
Loans and leases	33,435	5,192
Accruing and Nonaccruing Loans and Leases | National Lending | Warehouse finance
Financing Receivable, Past Due [Line Items]
Loans and leases	349,911	376,915
Accruing and Nonaccruing Loans and Leases | 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases	38,837	27,052
Accruing and Nonaccruing Loans and Leases | 30-59 Days Past Due | Total loans and leases held for investment
Financing Receivable, Past Due [Line Items]
Loans and leases	37,664	26,426
Accruing and Nonaccruing Loans and Leases | 30-59 Days Past Due | National Lending | Loans held for sale
Financing Receivable, Past Due [Line Items]
Loans and leases	1,173	626
Accruing and Nonaccruing Loans and Leases | 30-59 Days Past Due | National Lending | Term lending
Financing Receivable, Past Due [Line Items]
Loans and leases	28,694	13,898
Accruing and Nonaccruing Loans and Leases | 30-59 Days Past Due | National Lending | Asset-based lending
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Accruing and Nonaccruing Loans and Leases | 30-59 Days Past Due | National Lending | Factoring
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Accruing and Nonaccruing Loans and Leases | 30-59 Days Past Due | National Lending | Lease financing
Financing Receivable, Past Due [Line Items]
Loans and leases	1,944	6,865
Accruing and Nonaccruing Loans and Leases | 30-59 Days Past Due | National Lending | Insurance premium finance
Financing Receivable, Past Due [Line Items]
Loans and leases	2,666	2,159
Accruing and Nonaccruing Loans and Leases | 30-59 Days Past Due | National Lending | SBA/USDA
Financing Receivable, Past Due [Line Items]
Loans and leases	102	512
Accruing and Nonaccruing Loans and Leases | 30-59 Days Past Due | National Lending | Other commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Accruing and Nonaccruing Loans and Leases | 30-59 Days Past Due | National Lending | Commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	33,406	23,434
Accruing and Nonaccruing Loans and Leases | 30-59 Days Past Due | National Lending | Consumer finance
Financing Receivable, Past Due [Line Items]
Loans and leases	4,258	2,992
Accruing and Nonaccruing Loans and Leases | 30-59 Days Past Due | National Lending | Tax services
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Accruing and Nonaccruing Loans and Leases | 30-59 Days Past Due | National Lending | Warehouse finance
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Accruing and Nonaccruing Loans and Leases | 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases	12,472	12,117
Accruing and Nonaccruing Loans and Leases | 60-89 Days Past Due | Total loans and leases held for investment
Financing Receivable, Past Due [Line Items]
Loans and leases	11,686	11,568
Accruing and Nonaccruing Loans and Leases | 60-89 Days Past Due | National Lending | Loans held for sale
Financing Receivable, Past Due [Line Items]
Loans and leases	786	549
Accruing and Nonaccruing Loans and Leases | 60-89 Days Past Due | National Lending | Term lending
Financing Receivable, Past Due [Line Items]
Loans and leases	6,156	7,723
Accruing and Nonaccruing Loans and Leases | 60-89 Days Past Due | National Lending | Asset-based lending
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Accruing and Nonaccruing Loans and Leases | 60-89 Days Past Due | National Lending | Factoring
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Accruing and Nonaccruing Loans and Leases | 60-89 Days Past Due | National Lending | Lease financing
Financing Receivable, Past Due [Line Items]
Loans and leases	1,107	158
Accruing and Nonaccruing Loans and Leases | 60-89 Days Past Due | National Lending | Insurance premium finance
Financing Receivable, Past Due [Line Items]
Loans and leases	999	1,262
Accruing and Nonaccruing Loans and Leases | 60-89 Days Past Due | National Lending | SBA/USDA
Financing Receivable, Past Due [Line Items]
Loans and leases	79	0
Accruing and Nonaccruing Loans and Leases | 60-89 Days Past Due | National Lending | Other commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Accruing and Nonaccruing Loans and Leases | 60-89 Days Past Due | National Lending | Commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	8,341	9,143
Accruing and Nonaccruing Loans and Leases | 60-89 Days Past Due | National Lending | Consumer finance
Financing Receivable, Past Due [Line Items]
Loans and leases	3,345	2,425
Accruing and Nonaccruing Loans and Leases | 60-89 Days Past Due | National Lending | Tax services
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Accruing and Nonaccruing Loans and Leases | 60-89 Days Past Due | National Lending | Warehouse finance
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Accruing and Nonaccruing Loans and Leases | > 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases	24,259	27,950
Accruing and Nonaccruing Loans and Leases | > 89 Days Past Due | Total loans and leases held for investment
Financing Receivable, Past Due [Line Items]
Loans and leases	23,598	27,644
Accruing and Nonaccruing Loans and Leases | > 89 Days Past Due | National Lending | Loans held for sale
Financing Receivable, Past Due [Line Items]
Loans and leases	661	306
Accruing and Nonaccruing Loans and Leases | > 89 Days Past Due | National Lending | Term lending
Financing Receivable, Past Due [Line Items]
Loans and leases	14,385	11,136
Accruing and Nonaccruing Loans and Leases | > 89 Days Past Due | National Lending | Asset-based lending
Financing Receivable, Past Due [Line Items]
Loans and leases	123	123
Accruing and Nonaccruing Loans and Leases | > 89 Days Past Due | National Lending | Factoring
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Accruing and Nonaccruing Loans and Leases | > 89 Days Past Due | National Lending | Lease financing
Financing Receivable, Past Due [Line Items]
Loans and leases	2,161	4,828
Accruing and Nonaccruing Loans and Leases | > 89 Days Past Due | National Lending | Insurance premium finance
Financing Receivable, Past Due [Line Items]
Loans and leases	1,924	2,339
Accruing and Nonaccruing Loans and Leases | > 89 Days Past Due | National Lending | SBA/USDA
Financing Receivable, Past Due [Line Items]
Loans and leases	2,146	1,835
Accruing and Nonaccruing Loans and Leases | > 89 Days Past Due | National Lending | Other commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	0	91
Accruing and Nonaccruing Loans and Leases | > 89 Days Past Due | National Lending | Commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	20,739	20,352
Accruing and Nonaccruing Loans and Leases | > 89 Days Past Due | National Lending | Consumer finance
Financing Receivable, Past Due [Line Items]
Loans and leases	2,859	2,210
Accruing and Nonaccruing Loans and Leases | > 89 Days Past Due | National Lending | Tax services
Financing Receivable, Past Due [Line Items]
Loans and leases	0	5,082
Accruing and Nonaccruing Loans and Leases | > 89 Days Past Due | National Lending | Warehouse finance
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Accruing and Nonaccruing Loans and Leases | Total Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases	75,568	67,119
Accruing and Nonaccruing Loans and Leases | Total Past Due | Total loans and leases held for investment
Financing Receivable, Past Due [Line Items]
Loans and leases	72,948	65,638
Accruing and Nonaccruing Loans and Leases | Total Past Due | National Lending | Loans held for sale
Financing Receivable, Past Due [Line Items]
Loans and leases	2,620	1,481
Accruing and Nonaccruing Loans and Leases | Total Past Due | National Lending | Term lending
Financing Receivable, Past Due [Line Items]
Loans and leases	49,235	32,757
Accruing and Nonaccruing Loans and Leases | Total Past Due | National Lending | Asset-based lending
Financing Receivable, Past Due [Line Items]
Loans and leases	123	123
Accruing and Nonaccruing Loans and Leases | Total Past Due | National Lending | Factoring
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Accruing and Nonaccruing Loans and Leases | Total Past Due | National Lending | Lease financing
Financing Receivable, Past Due [Line Items]
Loans and leases	5,212	11,851
Accruing and Nonaccruing Loans and Leases | Total Past Due | National Lending | Insurance premium finance
Financing Receivable, Past Due [Line Items]
Loans and leases	5,589	5,760
Accruing and Nonaccruing Loans and Leases | Total Past Due | National Lending | SBA/USDA
Financing Receivable, Past Due [Line Items]
Loans and leases	2,327	2,347
Accruing and Nonaccruing Loans and Leases | Total Past Due | National Lending | Other commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	0	91
Accruing and Nonaccruing Loans and Leases | Total Past Due | National Lending | Commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	62,486	52,929
Accruing and Nonaccruing Loans and Leases | Total Past Due | National Lending | Consumer finance
Financing Receivable, Past Due [Line Items]
Loans and leases	10,462	7,627
Accruing and Nonaccruing Loans and Leases | Total Past Due | National Lending | Tax services
Financing Receivable, Past Due [Line Items]
Loans and leases	0	5,082
Accruing and Nonaccruing Loans and Leases | Total Past Due | National Lending | Warehouse finance
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Accruing and Nonaccruing Loans and Leases | Current
Financing Receivable, Past Due [Line Items]
Loans and leases	4,413,314	4,370,341
Accruing and Nonaccruing Loans and Leases | Current | Total loans and leases held for investment
Financing Receivable, Past Due [Line Items]
Loans and leases	4,346,416	4,294,043
Accruing and Nonaccruing Loans and Leases | Current | National Lending | Loans held for sale
Financing Receivable, Past Due [Line Items]
Loans and leases	66,898	76,298
Accruing and Nonaccruing Loans and Leases | Current | National Lending | Term lending
Financing Receivable, Past Due [Line Items]
Loans and leases	1,403,039	1,275,376
Accruing and Nonaccruing Loans and Leases | Current | National Lending | Asset-based lending
Financing Receivable, Past Due [Line Items]
Loans and leases	379,558	382,248
Accruing and Nonaccruing Loans and Leases | Current | National Lending | Factoring
Financing Receivable, Past Due [Line Items]
Loans and leases	335,953	358,344
Accruing and Nonaccruing Loans and Leases | Current | National Lending | Lease financing
Financing Receivable, Past Due [Line Items]
Loans and leases	183,677	171,541
Accruing and Nonaccruing Loans and Leases | Current | National Lending | Insurance premium finance
Financing Receivable, Past Due [Line Items]
Loans and leases	665,446	794,317
Accruing and Nonaccruing Loans and Leases | Current | National Lending | SBA/USDA
Financing Receivable, Past Due [Line Items]
Loans and leases	543,721	522,403
Accruing and Nonaccruing Loans and Leases | Current | National Lending | Other commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	160,628	166,000
Accruing and Nonaccruing Loans and Leases | Current | National Lending | Commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	3,672,022	3,670,229
Accruing and Nonaccruing Loans and Leases | Current | National Lending | Consumer finance
Financing Receivable, Past Due [Line Items]
Loans and leases	291,048	246,789
Accruing and Nonaccruing Loans and Leases | Current | National Lending | Tax services
Financing Receivable, Past Due [Line Items]
Loans and leases	33,435	110
Accruing and Nonaccruing Loans and Leases | Current | National Lending | Warehouse finance
Financing Receivable, Past Due [Line Items]
Loans and leases	349,911	376,915
Nonperforming Loans and Leases
Financing Receivable, Past Due [Line Items]
Loans and leases	39,481	56,212
Nonaccrual Balance	28,099	37,372
Nonperforming Loans and Leases | Total loans and leases held for investment
Financing Receivable, Past Due [Line Items]
Loans and leases	38,820	55,906
Nonaccrual Balance	28,099	37,372
Nonperforming Loans and Leases | National Lending | Loans held for sale
Financing Receivable, Past Due [Line Items]
Loans and leases	661	306
Nonaccrual Balance	0	0
Nonperforming Loans and Leases | National Lending | Term lending
Financing Receivable, Past Due [Line Items]
Loans and leases	21,984	19,061
Nonaccrual Balance	17,978	15,324
Nonperforming Loans and Leases | National Lending | Asset-based lending
Financing Receivable, Past Due [Line Items]
Loans and leases	4,593	18,082
Nonaccrual Balance	4,593	18,082
Nonperforming Loans and Leases | National Lending | Factoring
Financing Receivable, Past Due [Line Items]
Loans and leases	1,173	1,298
Nonaccrual Balance	1,173	1,298
Nonperforming Loans and Leases | National Lending | Lease financing
Financing Receivable, Past Due [Line Items]
Loans and leases	3,133	5,908
Nonaccrual Balance	1,645	1,666
Nonperforming Loans and Leases | National Lending | Insurance premium finance
Financing Receivable, Past Due [Line Items]
Loans and leases	1,924	2,339
Nonaccrual Balance	0	0
Nonperforming Loans and Leases | National Lending | SBA/USDA
Financing Receivable, Past Due [Line Items]
Loans and leases	3,154	1,835
Nonaccrual Balance	2,710	1,002
Nonperforming Loans and Leases | National Lending | Other commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	0	91
Nonaccrual Balance	0	0
Nonperforming Loans and Leases | National Lending | Commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	35,961	48,614
Nonaccrual Balance	28,099	37,372
Nonperforming Loans and Leases | National Lending | Consumer finance
Financing Receivable, Past Due [Line Items]
Loans and leases	2,859	2,210
Nonaccrual Balance	0	0
Nonperforming Loans and Leases | National Lending | Tax services
Financing Receivable, Past Due [Line Items]
Loans and leases	0	5,082
Nonaccrual Balance	0	0
Nonperforming Loans and Leases | National Lending | Warehouse finance
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Nonaccrual Balance	0	0
Nonperforming Loans and Leases | > 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases	11,382	18,840
Nonperforming Loans and Leases | > 89 Days Past Due | Total loans and leases held for investment
Financing Receivable, Past Due [Line Items]
Loans and leases	10,721	18,534
Nonperforming Loans and Leases | > 89 Days Past Due | National Lending | Loans held for sale
Financing Receivable, Past Due [Line Items]
Loans and leases	661	306
Nonperforming Loans and Leases | > 89 Days Past Due | National Lending | Term lending
Financing Receivable, Past Due [Line Items]
Loans and leases	4,006	3,737
Nonperforming Loans and Leases | > 89 Days Past Due | National Lending | Asset-based lending
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Nonperforming Loans and Leases | > 89 Days Past Due | National Lending | Factoring
Financing Receivable, Past Due [Line Items]
Loans and leases	0	0
Nonperforming Loans and Leases | > 89 Days Past Due | National Lending | Lease financing
Financing Receivable, Past Due [Line Items]
Loans and leases	1,488	4,242
Nonperforming Loans and Leases | > 89 Days Past Due | National Lending | Insurance premium finance
Financing Receivable, Past Due [Line Items]
Loans and leases	1,924	2,339
Nonperforming Loans and Leases | > 89 Days Past Due | National Lending | SBA/USDA
Financing Receivable, Past Due [Line Items]
Loans and leases	444	833
Nonperforming Loans and Leases | > 89 Days Past Due | National Lending | Other commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	0	91
Nonperforming Loans and Leases | > 89 Days Past Due | National Lending | Commercial finance
Financing Receivable, Past Due [Line Items]
Loans and leases	7,862	11,242
Nonperforming Loans and Leases | > 89 Days Past Due | National Lending | Consumer finance
Financing Receivable, Past Due [Line Items]
Loans and leases	2,859	2,210
Nonperforming Loans and Leases | > 89 Days Past Due | National Lending | Tax services
Financing Receivable, Past Due [Line Items]
Loans and leases	0	5,082
Nonperforming Loans and Leases | > 89 Days Past Due | National Lending | Warehouse finance
Financing Receivable, Past Due [Line Items]
Loans and leases	$ 0	$ 0