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Nature of Operations (Details) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
	Mar. 24, 2021 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) Office	Sep. 30, 2021 USD ($)	Dec. 31, 2021 Office
Nature of Operations
ESOP shares committed to be released		$ 107	$ 108
Percentage of shares of the outstanding stock sold				6.97%
Number of full service branch offices \| Office		13		13
Additional Paid-in capital
Nature of Operations
Cash Acquired from Acquisition	$ 5,400
William Penn Bank
Nature of Operations
Gross proceeds	$ 126,400
William Penn, MHC shares sold in public offering, net of offering costs (in shares) \| shares	12,640,035
Share price \| $ / shares	$ 10.00
Shares outstanding \| shares	776,647
Conversion of existing shares at 3.2585 exchange ratio	3.2585
Percentage of shares sold in offering	8.00%
Percentage of aggregate purchase price of common stock	100.00%
ESOP issued \| shares	881,130
ESOP shares committed to be released	$ 10,100
Ownership percentage held by parent (as a percent)		100.00%		100.00%