Employee Stock Ownership Plan (Additional Information) (Detail) - $ / shares	5 Months Ended
Oct. 06, 2008	Jun. 30, 2018	Sep. 30, 2017
Total ESOP shares	203,363	155,907	161,115
Employee Stock Ownership Plan (ESOP), Weighted Average Purchase Price of Shares Purchased	$ 10.00

Sum of the allocated, committed-to-be-released and suspense shares of the entity held by the plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109244661&loc=d3e17540-113929

Name:	us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant