Summary of Loan Portfolio Quality Indicators by Loan Class Recorded Investment (Detail) (USD $)	Jun. 30, 2013	Sep. 30, 2012
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	$ 55,727,894	$ 55,292,322
One To Four Family Owner Occupied
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	25,209,744	26,097,798
One To Four Family Owner Occupied \| Pass
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	24,380,805	25,261,976
One To Four Family Owner Occupied \| Substandard
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	828,939	835,822
One To Four Family Non Owner Occupied
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	17,286,603	17,855,304
One To Four Family Non Owner Occupied \| Pass
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	14,830,693	15,904,215
One To Four Family Non Owner Occupied \| Substandard
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	2,111,257	1,951,089
One To Four Family Non Owner Occupied \| Doubtful
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	344,653
Home Equity
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	2,462,511	2,172,247
Home Equity \| Pass
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	2,462,511	2,172,247
Mobile Home
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	1,952,121	2,068,672
Mobile Home \| Pass
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	1,819,190	1,814,197
Mobile Home \| Special Mention
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans		74,743
Mobile Home \| Substandard
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	132,931	179,732
Secured By Other Properties
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	2,917,522	2,613,025
Secured By Other Properties \| Pass
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	2,702,967	2,397,025
Secured By Other Properties \| Doubtful
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	214,555	216,000
Construction and Land Development
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	4,472,229	3,262,452
Construction and Land Development \| Pass
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	4,030,188	2,820,472
Construction and Land Development \| Substandard
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	442,041	441,980
Secured Commercial
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	1,422,499	1,212,534
Secured Commercial \| Pass
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	1,422,499	1,212,534
Savings
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	4,665	10,290
Savings \| Pass
Summary of Allowances for Credit Loss and Related Financing Receivables [Line Items]
Total loans	$ 4,665	$ 10,290

Fairmount Bancorp, Inc. 10-Q