Employee Stock Ownership Plan (Narrative) (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2017 USD ($) shares	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2018 shares
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Shares Held In Employee Stock Ownership Plan, Allocated	165,198
Compensation expense related to the ESOP including dividends | $	$ 3,300	$ 3,000	$ 3,000
Portion of compensation expense related to the ESOP attributable to changes in Company stock price | $	784	522	384
Dividends on unallocated ESOP shares in excess of debt service payments | $	$ 833	$ 813	$ 952
Forecast [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Shares Held In Employee Stock Ownership Plan, Committed-to-be-Released				165,198
Minimum [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Percentage of ESOP shares participant may diversify once age requirement is met	25.00%
Required age of participant in order to diversify ESOP shares, years	50
IPO [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Number of shares acquired by ESOP trust	3,024,574
Number of shares acquired by ESOP post corporate reorganization	6,846,728
ESOP loan maturity date	Sep. 30, 2013
Corporate Reorganization [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Number of shares acquired by ESOP trust	4,726,000
ESOP loan maturity date	Sep. 30, 2040