Note 4: Acquired Loans, Loss Sharing Agreements and FDIC Indemnification Assets: Schedule of Accretable Yield Changes for Acquired Loans (Details) - USD ($) $ in Thousands	3 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
TeamBank
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion	$ (1,042)	$ (1,563)	$ (1,834)
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference	327	1,157	506
TeamBank \| Balance, Beginning of Period
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Period Increase (Decrease)			3,805
TeamBank \| Balance, End of Period
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Period Increase (Decrease)	1,356	2,071	2,477
Vantus Bank
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion	(1,196)	(1,373)	(1,877)
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference	778	676	1,064
Vantus Bank \| Balance, Beginning of Period
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Period Increase (Decrease)			3,360
Vantus Bank \| Balance, End of Period
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Period Increase (Decrease)	1,432	1,850	2,547
Sun Security Bank
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion	(1,667)	(2,251)	(3,832)
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference	1,008	875	2,185
Sun Security Bank \| Balance, Beginning of Period
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Period Increase (Decrease)			5,924
Sun Security Bank \| Balance, End of Period
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Period Increase (Decrease)	2,242	2,901	4,277
InterBank
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion	(8,349)	(7,505)	(13,964)
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference	8,269	4,067	6,129
InterBank \| Balance, Beginning of Period
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Period Increase (Decrease)			16,347
InterBank \| Balance, End of Period
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Period Increase (Decrease)	4,994	5,074	8,512
Valley Bank
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion	(3,892)	(5,823)	(11,933)
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference	4,260	3,721	8,414
Valley Bank \| Balance, Beginning of Period
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Period Increase (Decrease)			8,316
Valley Bank \| Balance, End of Period
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Period Increase (Decrease)	$ 3,063	$ 2,695	$ 4,797

Change in the estimate of cash flows expected to be collected, after acquisition of a loan, which results in an increase in accretable yield (for example, if actual cash flows are significantly greater than previously expected). This relates to loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538

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- Definition

Amount of accretion recognized for the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities, with evidence of deterioration of credit quality.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544

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