Goodwill and Intangible Assets - Schedule of Acquired Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 8,147	$ 7,996
Accumulated Amortization	6,204	5,408
Estimated amortization expense	1,943	2,588
MSRs [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	873	722
Accumulated Amortization	225	144
Estimated amortization expense	648	578
Core deposit intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	7,274	7,274
Accumulated Amortization	5,979	5,264
Estimated amortization expense	$ 1,295	$ 2,010