Regulatory Matters (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jun. 30, 2018
The Bank of Greene County [Member]
Compliance with Regulatory Capital [Abstract]
Total risk-based capital, actual amount	$ 118,113	$ 102,549
Total risk-based capital, actual ratio	15.80%	15.50%
Total risk-based capital for capital adequacy purposes, amount	$ 59,842	$ 53,024
Total risk-based capital for capital adequacy purposes, ratio	8.00%	8.00%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount	$ 74,802	$ 66,280
Total risk-based capital to be well capitalized under prompt corrective action provisions, ratio	10.00%	10.00%
Total risk-based capital for capital conservation buffer, actual	7.79%	7.472%
Total risk-based capital for capital conservation buffer, required	2.50%	1.875%
Tier 1 risk-based capital, actual amount	$ 108,716	$ 94,148
Tier 1 risk-based capital, actual ratio	14.50%	14.20%
Tier 1 risk-based capital for capital adequacy purposes, amount	$ 44,881	$ 39,768
Tier 1 risk-based capital for capital adequacy purposes, ratio	6.00%	6.00%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount	$ 59,842	$ 53,024
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio	8.00%	8.00%
Tier 1 risk-based capital for capital conservation buffer, actual	8.534%	8.205%
Tier 1 risk-based capital for capital conservation buffer, required	2.50%	1.875%
Common equity tier 1 capital, actual amount	$ 108,716	$ 94,148
Common equity tier 1 capital, actual ratio	14.50%	14.20%
Common equity tier 1 capital for capital adequacy purposes, amount	$ 33,661	$ 29,826
Common equity tier 1 capital for capital adequacy purposes, ratio	4.50%	4.50%
Common equity tier 1 capital to be well capitalized under prompt corrective action provisions, amount	$ 48,621	$ 43,082
Common equity tier 1 capital to be well capitalized under prompt corrective action provisions, ratio	6.50%	6.50%
Common equity tier 1 capital for capital conservation buffer, actual	10.034%	9.705%
Common equity tier 1 capital for capital conservation buffer, required	2.50%	1.875%
Tier 1 leverage ratio, actual amount	$ 108,716	$ 94,148
Tier 1 leverage ratio, actual ratio	8.70%	8.20%
Tier 1 leverage ratio for capital adequacy purposes, amount	$ 50,049	$ 45,789
Tier 1 leverage ratio for capital adequacy purposes, ratio	4.00%	4.00%
Tier 1 leverage ratio to be well capitalized under prompt corrective action provisions, amount	$ 62,561	$ 57,236
Tier 1 leverage ratio to be well capitalized under prompt corrective action provisions, ratio	5.00%	5.00%
Tier 1 leverage ratio for capital conservation buffer, actual	4.689%	4.225%
Tier 1 leverage ratio for capital conservation buffer, required	2.50%	1.875%
Greene County Commercial Bank [Member]
Compliance with Regulatory Capital [Abstract]
Total risk-based capital, actual amount	$ 47,366	$ 40,286
Total risk-based capital, actual ratio	47.40%	47.10%
Total risk-based capital for capital adequacy purposes, amount	$ 7,996	$ 6,837
Total risk-based capital for capital adequacy purposes, ratio	8.00%	8.00%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount	$ 9,996	$ 8,546
Total risk-based capital to be well capitalized under prompt corrective action provisions, ratio	10.00%	10.00%
Total risk-based capital for capital conservation buffer, actual	39.387%	39.139%
Total risk-based capital for capital conservation buffer, required	2.50%	1.875%
Tier 1 risk-based capital, actual amount	$ 47,366	$ 40,286
Tier 1 risk-based capital, actual ratio	47.40%	47.10%
Tier 1 risk-based capital for capital adequacy purposes, amount	$ 5,997	$ 5,128
Tier 1 risk-based capital for capital adequacy purposes, ratio	6.00%	6.00%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount	$ 7,996	$ 6,837
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio	8.00%	8.00%
Tier 1 risk-based capital for capital conservation buffer, actual	41.387%	41.139%
Tier 1 risk-based capital for capital conservation buffer, required	2.50%	1.875%
Common equity tier 1 capital, actual amount	$ 47,366	$ 40,286
Common equity tier 1 capital, actual ratio	47.40%	47.10%
Common equity tier 1 capital for capital adequacy purposes, amount	$ 4,498	$ 3,846
Common equity tier 1 capital for capital adequacy purposes, ratio	4.50%	4.50%
Common equity tier 1 capital to be well capitalized under prompt corrective action provisions, amount	$ 6,497	$ 5,555
Common equity tier 1 capital to be well capitalized under prompt corrective action provisions, ratio	6.50%	6.50%
Common equity tier 1 capital for capital conservation buffer, actual	42.887%	42.639%
Common equity tier 1 capital for capital conservation buffer, required	2.50%	1.875%
Tier 1 leverage ratio, actual amount	$ 47,366	$ 40,286
Tier 1 leverage ratio, actual ratio	9.60%	9.10%
Tier 1 leverage ratio for capital adequacy purposes, amount	$ 19,678	$ 17,747
Tier 1 leverage ratio for capital adequacy purposes, ratio	4.00%	4.00%
Tier 1 leverage ratio to be well capitalized under prompt corrective action provisions, amount	$ 24,597	$ 22,184
Tier 1 leverage ratio to be well capitalized under prompt corrective action provisions, ratio	5.00%	5.00%
Tier 1 leverage ratio for capital conservation buffer, actual	5.628%	5.08%
Tier 1 leverage ratio for capital conservation buffer, required	2.50%	1.875%