Commitments and Contingent Liabilities (Details) - The Bank of Greene County [Member] - USD ($) $ in Thousands	Jun. 30, 2018	Jun. 30, 2017
Commitments [Abstract]
Total commitments	$ 95,487	$ 92,522
Unfunded Loan Commitments [Member]
Commitments [Abstract]
Total commitments	36,624	41,082
Unused Lines of Credit [Member]
Commitments [Abstract]
Total commitments	$ 58,863	$ 51,440