Investment Securities (Available For Sale Securities With Gross Unrealized Losses By Investment Category And Length Of Time Individual Securities Have Been In Continuous Loss Position) (Detail) $ in Thousands	Jun. 30, 2017 USD ($) Number	Sep. 30, 2016 USD ($) Number
Investments, Unrealized Loss Position [Line Items]
Securities available for sale, Continuous loss position less than twelve months, Number of investment positions	29	9
Securities available for sale, Continuous loss position more than twelve months, Number of Investment Positions | Number	3	2
Securities available for sale, Number of Investment Positions | Number	32	11
Securities available for sale, Continuous loss position less than twelve months, Fair Value	$ 24,399	$ 6,159
Securities available for sale, Continuous loss position more than twelve months, Fair Value	3,341	4,683
Securities available for sale, Continuous loss position	27,740	10,842
Securities available for sale, Continuous loss position less than twelve months, Gross Unrealized Losses	302	38
Securities available for sale, Continuous loss position more than twelve months, Gross Unrealized Losses	14	54
Securities available for sale, Continuous loss position, Gross Unrealized Losses	$ 316	$ 92
Agency Mortgage-Backed
Investments, Unrealized Loss Position [Line Items]
Securities available for sale, Continuous loss position less than twelve months, Number of investment positions	10
Securities available for sale, Continuous loss position less than twelve months, Fair Value	$ 9,946
Securities available for sale, Continuous loss position less than twelve months, Gross Unrealized Losses	$ 68
Agency CMO
Investments, Unrealized Loss Position [Line Items]
Securities available for sale, Continuous loss position less than twelve months, Number of investment positions	7	3
Securities available for sale, Continuous loss position more than twelve months, Number of Investment Positions	3	2
Securities available for sale, Continuous loss position less than twelve months, Fair Value	$ 7,389	$ 3,946
Securities available for sale, Continuous loss position more than twelve months, Fair Value	3,341	4,683
Securities available for sale, Continuous loss position less than twelve months, Gross Unrealized Losses	42	12
Securities available for sale, Continuous loss position more than twelve months, Gross Unrealized Losses	$ 14	$ 54
Municipal obligations
Investments, Unrealized Loss Position [Line Items]
Securities available for sale, Continuous loss position less than twelve months, Number of investment positions	10	4
Securities available for sale, Continuous loss position less than twelve months, Fair Value	$ 6,938	$ 2,147
Securities available for sale, Continuous loss position less than twelve months, Gross Unrealized Losses	$ 173	$ 19
Privately-issued ABS
Investments, Unrealized Loss Position [Line Items]
Securities available for sale, Continuous loss position less than twelve months, Number of investment positions | Number		2
Securities available for sale, Continuous loss position less than twelve months, Fair Value		$ 66
Securities available for sale, Continuous loss position less than twelve months, Gross Unrealized Losses		$ 7
Privately issued CMO [Member]
Investments, Unrealized Loss Position [Line Items]
Securities available for sale, Continuous loss position less than twelve months, Number of investment positions	2
Securities available for sale, Continuous loss position less than twelve months, Fair Value	$ 126
Securities available for sale, Continuous loss position less than twelve months, Gross Unrealized Losses	$ 19