LOANS AND LEASES, NET - Allowance for Loan Losses and Recorded Investment in Loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Sep. 30, 2018
Allowance for Credit Losses [Roll Forward]
Beginning balance	$ 13,040	$ 7,534
Provision (recovery) for loan losses	9,099	1,068
Charge offs	(2,804)	(160)
Recoveries	1,955	420
Ending balance	21,290	8,862
Ending balance: individually evaluated for impairment			$ 134	$ 0
Ending balance: collectively evaluated for impairment			21,156	13,040
Total	13,040	7,534	21,290	13,040
Loans:
Ending balance: individually evaluated for impairment			11,102	15,611
Ending balance: collectively evaluated for impairment			3,317,206	2,929,378
Loans and Leases Receivable, Gross			3,328,308	2,944,989
Financing Receivable [Member]
Loans:
Loans and Leases Receivable, Gross			2,149,243	1,846,283
Financing Receivable [Member] | Asset Based Lending [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	107
Provision (recovery) for loan losses	2,164
Charge offs	(262)
Recoveries	56
Ending balance	2,065
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			2,065	107
Total	107		2,065	107
Loans:
Ending balance: individually evaluated for impairment			2,371	1,404
Ending balance: collectively evaluated for impairment			551,701	476,513
Loans and Leases Receivable, Gross			554,072	477,917
Financing Receivable [Member] | Factoring [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	64
Provision (recovery) for loan losses	1,223
Charge offs	(250)
Recoveries	26
Ending balance	1,062
Ending balance: individually evaluated for impairment			134	0
Ending balance: collectively evaluated for impairment			928	64
Total	64		1,062	64
Loans:
Ending balance: individually evaluated for impairment			1,680	3,331
Ending balance: collectively evaluated for impairment			283,232	280,890
Loans and Leases Receivable, Gross			284,912	284,221
Financing Receivable [Member] | Finance Leases Portfolio Segment [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	59
Provision (recovery) for loan losses	(130)
Charge offs	(418)
Recoveries	1,572
Ending balance	1,084
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			1,084	59
Total	59		1,084	59
Loans:
Ending balance: individually evaluated for impairment			5,000	8,877
Ending balance: collectively evaluated for impairment			285,889	256,438
Loans and Leases Receivable, Gross			290,889	265,315
Financing Receivable [Member] | Commercial Insurance Premium Finance [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	1,031	796
Provision (recovery) for loan losses	93	51
Charge offs	(208)	(129)
Recoveries	56	7
Ending balance	972	725
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			972	1,031
Total	1,031	796	972	1,031
Loans:
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			330,712	337,877
Loans and Leases Receivable, Gross			330,712	337,877
Financing Receivable [Member] | SBA/USDA [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	13
Provision (recovery) for loan losses	240
Charge offs	0
Recoveries	0
Ending balance	253
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			253	13
Total	13		253	13
Loans:
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			67,893	59,374
Loans and Leases Receivable, Gross			67,893	59,374
Financing Receivable [Member] | Other Commercial Finance [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	28	4
Provision (recovery) for loan losses	263	0
Charge offs	0	0
Recoveries	0	0
Ending balance	291	4
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			291	28
Total	28	4	291	28
Loans:
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			89,402	85,145
Loans and Leases Receivable, Gross			89,402	85,145
Financing Receivable [Member] | Commercial Operating [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	1,302	800
Provision (recovery) for loan losses	3,853	51
Charge offs	(1,138)	(129)
Recoveries	1,710	7
Ending balance	5,727	729
Ending balance: individually evaluated for impairment			134	0
Ending balance: collectively evaluated for impairment			5,593	1,302
Total	1,302	800	5,727	1,302
Loans:
Ending balance: individually evaluated for impairment			9,051	13,612
Ending balance: collectively evaluated for impairment			1,608,829	1,496,237
Loans and Leases Receivable, Gross			1,617,880	1,509,849
Financing Receivable [Member] | Consumer Credit Products [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	785
Provision (recovery) for loan losses	366
Charge offs	0
Recoveries	0
Ending balance	1,151
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			1,151	785
Total	785		1,151	785
Loans:
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			96,144	80,605
Loans and Leases Receivable, Gross			96,144	80,605
Financing Receivable [Member] | Other Consumer Finance [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	2,820
Provision (recovery) for loan losses	3,023
Charge offs	(1,624)
Recoveries	3
Ending balance	4,222
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			4,222	2,820
Total	2,820		4,222	2,820
Loans:
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			182,510	189,756
Loans and Leases Receivable, Gross			182,510	189,756
Financing Receivable [Member] | Consumer [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	3,605
Provision (recovery) for loan losses	3,389
Charge offs	(1,624)
Recoveries	3
Ending balance	5,373
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			5,373	3,605
Total	3,605		5,373	3,605
Loans:
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			278,654	270,361
Loans and Leases Receivable, Gross			278,654	270,361
Financing Receivable [Member] | Tax Services [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	0	5
Provision (recovery) for loan losses	1,496	1,017
Charge offs	(42)	0
Recoveries	92	413
Ending balance	1,546	1,435
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			1,546	0
Total	0	5	1,546	0
Loans:
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			76,575	1,073
Loans and Leases Receivable, Gross			76,575	1,073
Financing Receivable [Member] | Warehouse Agreement Borrowings [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	65
Provision (recovery) for loan losses	111
Charge offs	0
Recoveries	0
Ending balance	176
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			176	65
Total	65		176	65
Loans:
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			176,134	65,000
Loans and Leases Receivable, Gross			176,134	65,000
Financing Receivable [Member] | National Lending [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	4,972	805
Provision (recovery) for loan losses	8,849	1,068
Charge offs	(2,804)	(129)
Recoveries	1,805	420
Ending balance	12,822	2,164
Ending balance: individually evaluated for impairment			134	0
Ending balance: collectively evaluated for impairment			12,688	4,972
Total	4,972	805	12,822	4,972
Loans:
Ending balance: individually evaluated for impairment			9,051	13,612
Ending balance: collectively evaluated for impairment			2,140,192	1,832,671
Loans and Leases Receivable, Gross			2,149,243	1,846,283
Loans Receivable [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	8,068	6,729
Provision (recovery) for loan losses	250	0
Charge offs	0	(31)
Recoveries	150	0
Ending balance	8,468	6,698
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			8,468	8,068
Total	8,068	6,729	8,468	8,068
Loans:
Ending balance: individually evaluated for impairment			2,051	1,999
Ending balance: collectively evaluated for impairment			1,177,014	1,096,707
Loans and Leases Receivable, Gross			1,179,065	1,098,706
Loans Receivable [Member] | Unallocated [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance		526
Provision (recovery) for loan losses		374
Charge offs		0
Recoveries		0
Ending balance		900
Total		526
Loans Receivable [Member] | Commercial and Multi-Family Real Estate [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	6,220	2,820
Provision (recovery) for loan losses	350	329
Charge offs	0	0
Recoveries	0	0
Ending balance	6,570	3,149
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			6,570	6,220
Total	6,220	2,820	6,570	6,220
Loans:
Ending balance: individually evaluated for impairment			402	451
Ending balance: collectively evaluated for impairment			863,351	790,439
Loans and Leases Receivable, Gross			863,753	790,890
Loans Receivable [Member] | 1-4 Family Real Estate [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	632	809
Provision (recovery) for loan losses	87	(113)
Charge offs	0	(31)
Recoveries	0	0
Ending balance	719	665
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			719	632
Total	632	809	719	632
Loans:
Ending balance: individually evaluated for impairment			138	94
Ending balance: collectively evaluated for impairment			256,203	247,224
Loans and Leases Receivable, Gross			256,341	247,318
Loans Receivable [Member] | Agricultural Operating [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	1,216	2,574
Provision (recovery) for loan losses	(187)	(590)
Charge offs	0	0
Recoveries	150	0
Ending balance	1,179	1,984
Ending balance: individually evaluated for impairment			0	0
Ending balance: collectively evaluated for impairment			1,179	1,216
Total	$ 1,216	$ 2,574	1,179	1,216
Loans:
Ending balance: individually evaluated for impairment			1,511	1,454
Ending balance: collectively evaluated for impairment			57,460	59,044
Loans and Leases Receivable, Gross			$ 58,971	$ 60,498