CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Interest and dividend income:
Loans receivable, including fees		$ 52,117	$ 36,187	$ 29,565
Mortgage-backed securities		16,571	15,771	13,979
Other investments		39,415	29,438	18,063
Total interest and dividend income		108,103	81,396	61,607
Interest expense:
Deposits		6,051	614	726
FHLB advances and other borrowings		8,822	3,477	1,661
Total interest expense		14,873	4,091	2,387
Net interest income		93,230	77,305	59,220
Provision for loan losses		10,589	4,605	1,465
Net interest income after provision for loan losses		82,641	72,700	57,755
Non-interest income:
Refund transfer product fees		38,956	23,347	63
Tax advance product fees		31,913	1,575	0
Card fees		94,707	70,533	54,542
Loan fees		3,882	3,374	2,348
Bank-owned life insurance income		2,216	1,656	2,030
Deposit fees		736	603	593
Loss on sale of securities available-for-sale, net (Includes ($493), ($326), and ($1,634) reclassified from accumulated other comprehensive income (loss) for net gains (losses) on available for sale securities for the fiscal years ended September 30, 2017, 2016 and 2015, respectively)		(493)	(326)	(1,634)
Loss (gain) on foreclosed real estate		(6)	0	28
Other income		261	8	204
Total non-interest income		172,172	100,770	58,174
Non-interest expense:
Compensation and benefits		88,728	61,675	46,493
Refund transfer product expense		11,885	8,648	3
Tax advance product expense		3,241	0	0
Card processing expense		24,130	22,263	16,508
Occupancy and equipment expense		16,465	13,999	11,399
Legal and consulting expense		8,384	4,824	4,978
Marketing		1,449	1,334	1,347
Data processing expense		2,117	1,972	1,537
Amortization expense		12,362	4,828	1,349
Intangible impairment		10,248	0	0
Other expense		20,654	15,105	12,892
Total non-interest expense		199,663	134,648	96,506
Income before income tax expense		55,150	38,822	19,423
Income tax expense (Includes ($185), ($118), and ($597) income tax expense (benefit) reclassified from accumulated other comprehensive income (loss) for the fiscal years ended September 30, 2017, 2016 and 2015, respectively)		10,233	5,602	1,368
Net Income		$ 44,917	$ 33,220	$ 18,055
Earnings per common share (1):
Basic (in dollars per share)	[1]	$ 4.86	$ 3.93	$ 2.68
Diluted (in dollars per share)	[1]	$ 4.83	3.91	$ 2.66
Accounting Standards Update 2015-06 [Member]
Earnings per common share (1):
Basic (in dollars per share)			3.93
Diluted (in dollars per share)			3.91
Accounting Standards Update 2015-06 [Member] | Scenario, Previously Reported [Member]
Earnings per common share (1):
Basic (in dollars per share)			3.95
Diluted (in dollars per share)			$ 3.92

[1] See Reclassification and Revision of Prior Period Balances under Note 1 Summary of Significant Accounting Policies for additional information describing adjustments made to the Company's EPS calculation. Basic EPS for the fiscal year ended September 30, 2016 of $3.95 was corrected to $3.93 and diluted EPS of $3.92 was corrected to $3.91.