LOANS AND LEASES, NET - Credit Quality Indicator (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025	Sep. 30, 2025
Financing Receivable, Credit Quality Indicator [Line Items]
Total gross loans and leases	$ 4,867,165		$ 4,867,165		$ 4,664,908
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	603,791		603,791		1,068,007
Year two	772,017		772,017		544,490
Year three	271,781		271,781		428,620
Year four	330,458		330,458		238,299
Year five	192,661		192,661		76,450
Prior	181,666		181,666		133,867
Revolving Loans and Leases	1,070,130		1,070,130		1,125,666
Total gross loans and leases	3,422,504		3,422,504		3,615,399
Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	44,545		44,545		81,912
Year two	173,328		173,328		81,624
Year three	243,681		243,681		71,304
Year four	65,700		65,700		20,334
Year five	16,142		16,142		30,632
Prior	31,490		31,490		16,955
Revolving Loans and Leases	347,361		347,361		269,759
Total gross loans and leases	922,247		922,247		572,520
Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	355		355		2,738
Year two	52,251		52,251		70,280
Year three	13,822		13,822		3,985
Year four	801		801		826
Year five	1,398		1,398		11,585
Prior	5,353		5,353		1,147
Revolving Loans and Leases	32,935		32,935		32,096
Total gross loans and leases	106,915		106,915		122,657
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	2,100		2,100		37,297
Year two	27,306		27,306		27,842
Year three	30,352		30,352		56,392
Year four	79,081		79,081		23,192
Year five	24,041		24,041		22,373
Prior	65,827		65,827		51,488
Revolving Loans and Leases	18,562		18,562		26,267
Total gross loans and leases	247,269		247,269		244,851
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	45		45		221
Year two	0		0		3,251
Year three	900		900		2,516
Year four	818		818		3,854
Year five	2,962		2,962		1,652
Prior	4,416		4,416		70
Revolving Loans and Leases	9,143		9,143		2,164
Total gross loans and leases	18,284		18,284		13,728
Total
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	650,836		650,836		1,190,175
Year two	1,024,902		1,024,902		727,487
Year three	560,536		560,536		562,817
Year four	476,858		476,858		286,505
Year five	237,204		237,204		142,692
Prior	288,752		288,752		203,527
Revolving Loans and Leases	1,478,131		1,478,131		1,455,952
Total gross loans and leases	4,717,219		4,717,219		4,569,155
National Lending | Total
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, Writeoffs			0		74
Year two, Writeoffs			224		8,762
Year three, Writeoffs			3,043		5,380
Year four, Writeoffs			2,568		3,347
Year five, Writeoffs			1,240		2,051
Prior, Writeoffs			3,680		1,531
Revolving Loans and Leases, Writeoffs			6,085		7,090
Total, Writeoffs			16,840		28,235
National Lending | Term lending
Financing Receivable, Credit Quality Indicator [Line Items]
Total, Writeoffs	7,180	$ 6,208	8,261	$ 14,583
National Lending | Term lending | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	516,856		516,856		935,599
Year two	637,643		637,643		399,968
Year three	217,616		217,616		298,678
Year four	228,868		228,868		99,820
Year five	81,938		81,938		43,216
Prior	76,235		76,235		35,971
Revolving Loans and Leases	0		0		0
Total gross loans and leases	1,759,156		1,759,156		1,813,252
National Lending | Term lending | Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	43,756		43,756		65,674
Year two	166,651		166,651		71,326
Year three	207,328		207,328		68,737
Year four	65,311		65,311		7,222
Year five	2,758		2,758		28,882
Prior	28,361		28,361		13,357
Revolving Loans and Leases	0		0		0
Total gross loans and leases	514,165		514,165		255,198
National Lending | Term lending | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		56
Year two	51,299		51,299		68,989
Year three	11,783		11,783		3,762
Year four	801		801		826
Year five	1,096		1,096		11,078
Prior	4,755		4,755		65
Revolving Loans and Leases	0		0		0
Total gross loans and leases	69,734		69,734		84,776
National Lending | Term lending | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	2,100		2,100		29,792
Year two	21,135		21,135		24,666
Year three	26,530		26,530		37,845
Year four	62,344		62,344		14,137
Year five	11,996		11,996		16,050
Prior	26,233		26,233		19,995
Revolving Loans and Leases	0		0		0
Total gross loans and leases	150,338		150,338		142,485
National Lending | Term lending | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		564
Year three	362		362		774
Year four	818		818		3,854
Year five	2,962		2,962		1,615
Prior	4,320		4,320		22
Revolving Loans and Leases	0		0		0
Total gross loans and leases	8,462		8,462		6,829
National Lending | Term lending | Total
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	562,712		562,712		1,031,121
Year two	876,728		876,728		565,513
Year three	463,619		463,619		409,796
Year four	358,142		358,142		125,859
Year five	100,750		100,750		100,841
Prior	139,904		139,904		69,410
Revolving Loans and Leases	0		0		0
Total gross loans and leases	2,501,855		2,501,855		2,302,540
Year one, Writeoffs			0		0
Year two, Writeoffs			0		7,818
Year three, Writeoffs			2,375		4,492
Year four, Writeoffs			988		3,257
Year five, Writeoffs			1,240		991
Prior, Writeoffs			3,658		419
Revolving Loans and Leases, Writeoffs			0		0
Total, Writeoffs			8,261		16,977
National Lending | Asset-based lending
Financing Receivable, Credit Quality Indicator [Line Items]
Total, Writeoffs	6,085	172	6,085	172
National Lending | Asset-based lending | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		0
Year three	0		0		0
Year four	0		0		0
Year five	0		0		0
Prior	0		0		0
Revolving Loans and Leases	299,174		299,174		301,128
Total gross loans and leases	299,174		299,174		301,128
National Lending | Asset-based lending | Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		0
Year three	0		0		0
Year four	0		0		0
Year five	0		0		0
Prior	0		0		0
Revolving Loans and Leases	304,962		304,962		233,541
Total gross loans and leases	304,962		304,962		233,541
National Lending | Asset-based lending | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		0
Year three	0		0		0
Year four	0		0		0
Year five	0		0		0
Prior	0		0		0
Revolving Loans and Leases	31,163		31,163		31,702
Total gross loans and leases	31,163		31,163		31,702
National Lending | Asset-based lending | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		0
Year three	0		0		0
Year four	0		0		0
Year five	0		0		0
Prior	0		0		0
Revolving Loans and Leases	17,135		17,135		24,730
Total gross loans and leases	17,135		17,135		24,730
National Lending | Asset-based lending | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		0
Year three	0		0		0
Year four	0		0		0
Year five	0		0		0
Prior	0		0		0
Revolving Loans and Leases	7,786		7,786		2,164
Total gross loans and leases	7,786		7,786		2,164
National Lending | Asset-based lending | Total
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		0
Year three	0		0		0
Year four	0		0		0
Year five	0		0		0
Prior	0		0		0
Revolving Loans and Leases	660,220		660,220		593,265
Total gross loans and leases	660,220		660,220		593,265
Year one, Writeoffs			0		0
Year two, Writeoffs			0		0
Year three, Writeoffs			0		0
Year four, Writeoffs			0		0
Year five, Writeoffs			0		0
Prior, Writeoffs			0		0
Revolving Loans and Leases, Writeoffs			6,085		5,611
Total, Writeoffs			6,085		5,611
National Lending | Factoring
Financing Receivable, Credit Quality Indicator [Line Items]
Total, Writeoffs	0	96	0	170
National Lending | Factoring | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		0
Year three	0		0		0
Year four	0		0		0
Year five	0		0		0
Prior	0		0		0
Revolving Loans and Leases	166,314		166,314		179,352
Total gross loans and leases	166,314		166,314		179,352
National Lending | Factoring | Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		0
Year three	0		0		0
Year four	0		0		0
Year five	0		0		0
Prior	0		0		0
Revolving Loans and Leases	42,399		42,399		36,218
Total gross loans and leases	42,399		42,399		36,218
National Lending | Factoring | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		0
Year three	0		0		0
Year four	0		0		0
Year five	0		0		0
Prior	0		0		0
Revolving Loans and Leases	1,772		1,772		394
Total gross loans and leases	1,772		1,772		394
National Lending | Factoring | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		0
Year three	0		0		0
Year four	0		0		0
Year five	0		0		0
Prior	0		0		0
Revolving Loans and Leases	1,427		1,427		1,537
Total gross loans and leases	1,427		1,427		1,537
National Lending | Factoring | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0
Year two	0		0
Year three	0		0
Year four	0		0
Year five	0		0
Prior	0		0
Revolving Loans and Leases	1,357		1,357
Total gross loans and leases	1,357		1,357
National Lending | Factoring | Total
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		0
Year three	0		0		0
Year four	0		0		0
Year five	0		0		0
Prior	0		0		0
Revolving Loans and Leases	213,269		213,269		217,501
Total gross loans and leases	213,269		213,269		217,501
Year one, Writeoffs			0		0
Year two, Writeoffs			0		0
Year three, Writeoffs			0		0
Year four, Writeoffs			0		0
Year five, Writeoffs			0		0
Prior, Writeoffs			0		0
Revolving Loans and Leases, Writeoffs			0		1,479
Total, Writeoffs			0		1,479
National Lending | Lease financing
Financing Receivable, Credit Quality Indicator [Line Items]
Total, Writeoffs	15	1,019	37	1,082
National Lending | Lease financing | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	14,553		14,553		43,710
Year two	38,223		38,223		20,259
Year three	15,200		15,200		36,483
Year four	30,390		30,390		2,270
Year five	1,475		1,475		1,089
Prior	2,296		2,296		4,439
Revolving Loans and Leases	0		0		0
Total gross loans and leases	102,137		102,137		108,250
National Lending | Lease financing | Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	456		456		13,587
Year two	3,980		3,980		5,181
Year three	4,474		4,474		13
Year four	389		389		635
Year five	0		0		1,059
Prior	27		27		0
Revolving Loans and Leases	0		0		0
Total gross loans and leases	9,326		9,326		20,475
National Lending | Lease financing | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		941
Year three	254		254		223
Year four	0		0		0
Year five	302		302		181
Prior	299		299		44
Revolving Loans and Leases	0		0		0
Total gross loans and leases	855		855		1,389
National Lending | Lease financing | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		7,190
Year two	2,712		2,712		0
Year three	0		0		5,375
Year four	5,036		5,036		1,377
Year five	908		908		4,088
Prior	5,883		5,883		905
Revolving Loans and Leases	0		0		0
Total gross loans and leases	14,539		14,539		18,935
National Lending | Lease financing | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	45		45		0
Year two	0		0		0
Year three	0		0		150
Year four	0		0		0
Year five	0		0		37
Prior	0		0		0
Revolving Loans and Leases	0		0		0
Total gross loans and leases	45		45		187
National Lending | Lease financing | Total
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	15,054		15,054		64,487
Year two	44,915		44,915		26,381
Year three	19,928		19,928		42,244
Year four	35,815		35,815		4,282
Year five	2,685		2,685		6,454
Prior	8,505		8,505		5,388
Revolving Loans and Leases	0		0		0
Total gross loans and leases	126,902		126,902		149,236
Year one, Writeoffs			0		0
Year two, Writeoffs			0		0
Year three, Writeoffs			0		320
Year four, Writeoffs			15		0
Year five, Writeoffs			0		1,005
Prior, Writeoffs			22		101
Revolving Loans and Leases, Writeoffs			0		0
Total, Writeoffs			37		1,426
National Lending | Insurance premium finance
Financing Receivable, Credit Quality Indicator [Line Items]
Total, Writeoffs				93
National Lending | Insurance premium finance | Total
Financing Receivable, Credit Quality Indicator [Line Items]
Year one, Writeoffs					0
Year two, Writeoffs					62
Year three, Writeoffs					31
Year four, Writeoffs					0
Year five, Writeoffs					0
Prior, Writeoffs					0
Revolving Loans and Leases, Writeoffs					0
Total, Writeoffs					93
National Lending | SBA/USDA
Financing Receivable, Credit Quality Indicator [Line Items]
Total, Writeoffs	1,981	609	2,457	906
National Lending | SBA/USDA | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	70,432		70,432		79,928
Year two	88,391		88,391		61,063
Year three	29,474		29,474		93,459
Year four	71,200		71,200		136,075
Year five	109,248		109,248		19,674
Prior	49,065		49,065		30,962
Revolving Loans and Leases	0		0		0
Total gross loans and leases	417,810		417,810		421,161
National Lending | SBA/USDA | Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	333		333		2,651
Year two	2,697		2,697		5,117
Year three	31,879		31,879		136
Year four	0		0		12,477
Year five	13,384		13,384		691
Prior	3,102		3,102		3,598
Revolving Loans and Leases	0		0		0
Total gross loans and leases	51,395		51,395		24,670
National Lending | SBA/USDA | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	355		355		2,682
Year two	952		952		350
Year three	1,785		1,785		0
Year four	0		0		0
Year five	0		0		326
Prior	299		299		1,038
Revolving Loans and Leases	0		0		0
Total gross loans and leases	3,391		3,391		4,396
National Lending | SBA/USDA | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		315
Year two	3,459		3,459		3,176
Year three	3,822		3,822		12,721
Year four	11,278		11,278		7,678
Year five	11,137		11,137		2,235
Prior	33,711		33,711		30,588
Revolving Loans and Leases	0		0		0
Total gross loans and leases	63,407		63,407		56,713
National Lending | SBA/USDA | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		221
Year two	0		0		2,687
Year three	538		538		1,592
Year four	0		0		0
Year five	0		0		0
Prior	96		96		48
Revolving Loans and Leases	0		0		0
Total gross loans and leases	634		634		4,548
National Lending | SBA/USDA | Total
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	71,120		71,120		85,797
Year two	95,499		95,499		72,393
Year three	67,498		67,498		107,908
Year four	82,478		82,478		156,230
Year five	133,769		133,769		22,926
Prior	86,273		86,273		66,234
Revolving Loans and Leases	0		0		0
Total gross loans and leases	536,637		536,637		511,488
Year one, Writeoffs			0		74
Year two, Writeoffs			224		882
Year three, Writeoffs			668		537
Year four, Writeoffs			1,565		90
Year five, Writeoffs			0		55
Prior, Writeoffs			0		1,011
Revolving Loans and Leases, Writeoffs			0		0
Total, Writeoffs			2,457		2,649
National Lending | Other commercial finance
Financing Receivable, Credit Quality Indicator [Line Items]
Total, Writeoffs	0	0	0	0
National Lending | Other commercial finance | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	1,950		1,950		8,770
Year two	7,760		7,760		63,200
Year three	9,491		9,491		0
Year four	0		0		134
Year five	0		0		12,471
Prior	54,070		54,070		62,495
Revolving Loans and Leases	0		0		0
Total gross loans and leases	73,271		73,271		147,070
National Lending | Other commercial finance | Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Year one					0
Year two					0
Year three					2,418
Year four					0
Year five					0
Prior					0
Revolving Loans and Leases					0
Total gross loans and leases					2,418
National Lending | Other commercial finance | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		0
Year three	0		0		451
Year four	423		423		0
Year five	0		0		0
Prior	0		0		0
Revolving Loans and Leases	0		0		0
Total gross loans and leases	423		423		451
National Lending | Other commercial finance | Total
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	1,950		1,950		8,770
Year two	7,760		7,760		63,200
Year three	9,491		9,491		2,869
Year four	423		423		134
Year five	0		0		12,471
Prior	54,070		54,070		62,495
Revolving Loans and Leases	0		0		0
Total gross loans and leases	73,694		73,694		149,939
Year one, Writeoffs			0		0
Year two, Writeoffs			0		0
Year three, Writeoffs			0		0
Year four, Writeoffs			0		0
Year five, Writeoffs			0		0
Prior, Writeoffs			0		0
Revolving Loans and Leases, Writeoffs			0		0
Total, Writeoffs			0		0
National Lending | Warehouse finance
Financing Receivable, Credit Quality Indicator [Line Items]
Total, Writeoffs	0	$ 0	0	$ 0
National Lending | Warehouse finance | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		0
Year three	0		0		0
Year four	0		0		0
Year five	0		0		0
Prior	0		0		0
Revolving Loans and Leases	604,642		604,642		645,186
Total gross loans and leases	604,642		604,642		645,186
National Lending | Warehouse finance | Total
Financing Receivable, Credit Quality Indicator [Line Items]
Year one	0		0		0
Year two	0		0		0
Year three	0		0		0
Year four	0		0		0
Year five	0		0		0
Prior	0		0		0
Revolving Loans and Leases	604,642		604,642		645,186
Total gross loans and leases	$ 604,642		604,642		645,186
Year one, Writeoffs			0		0
Year two, Writeoffs			0		0
Year three, Writeoffs			0		0
Year four, Writeoffs			0		0
Year five, Writeoffs			0		0
Prior, Writeoffs			0		0
Revolving Loans and Leases, Writeoffs			0		0
Total, Writeoffs			$ 0		$ 0