OTHER REAL ESTATE OWNED - Schedule Of (Gain) Loss On Other Real Estate Owned (Detail) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
REAL ESTATE DEVELOPMENT AND CONSTRUCTION
Net gain on sales	$ (74)	$ (16)	$ (78)
Operating expenses, net of rental income	10	15	21
Profit (Loss) from Real Estate Operations	$ (64)	$ (1)	$ (57)

This element represents the total of the costs related to real estate revenues, including management, leasing, and development services.

No definition available.

+ Details

Name:	fsfg_CostOfRealEstateRevenues
Namespace Prefix:	fsfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The net gain (loss) resulting from sales and other disposals of other real estate owned, increases (decreases) in the valuation allowance for foreclosed real estate, and write-downs of other real estate owned after acquisition or physical possession.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.14(d))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

+ Details

Name:	us-gaap_GainsLossesOnSalesOfOtherRealEstate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The net cost of operation of other real estate (including provisions for real estate losses, rental income, and gains and losses on sales of real estate).

+ References

+ Details

Name:	us-gaap_ProfitLossFromRealEstateOperations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_RealEstateAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration