Commitments and Contingent Liabilities (Details) - The Bank of Greene County [Member] - USD ($) $ in Thousands	Jun. 30, 2017	Jun. 30, 2016
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total commitments	$ 92,522	$ 72,019
Unfunded Loan Commitments [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total commitments	41,082	41,383
Unused Lines of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total commitments	$ 51,440	$ 30,636