Regulatory Matters (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Jun. 30, 2016
The Bank of Greene County [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total risk-based capital, actual amount	$ 87,719	$ 76,666
Total risk-based capital, actual ratio	15.80%	16.30%
Total risk-based capital for capital adequacy purposes, amount	$ 44,433	$ 37,577
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	$ 55,542	$ 46,972
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	7.794%	8.322%
Total risk-based capital for capital conservation buffer, required	1.25%	0.625%
Tier 1 risk-based capital, actual amount	$ 80,671	$ 70,709
Tier 1 risk-based capital, actual ratio	14.50%	15.10%
Tier 1 risk-based capital for capital adequacy purposes, amount	$ 33,325	$ 28,183
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	$ 44,433	$ 37,577
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	8.525%	9.054%
Tier 1 risk-based capital for capital conservation buffer, required	1.25%	0.625%
Common equity tier 1 capital, actual amount	$ 80,671	$ 70,709
Common equity tier 1 capital, actual ratio	14.50%	15.10%
Common equity tier 1 capital for capital adequacy purposes, amount	$ 24,994	$ 21,137
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	$ 36,102	$ 30,532
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	10.024%	10.554%
Common equity tier 1 capital for capital conservation buffer, required	1.25%	0.625%
Tier 1 leverage ratio, actual amount	$ 80,671	$ 70,709
Tier 1 leverage ratio, actual ratio	8.50%	8.40%
Tier 1 leverage ratio for capital adequacy purposes, amount	$ 38,056	$ 33,815
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	$ 47,571	$ 42,268
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	4.479%	4.364%
Tier 1 leverage ratio for capital conservation buffer, required	1.25%	0.625%
Greene County Commercial Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total risk-based capital, actual amount	$ 30,095	$ 23,065
Total risk-based capital, actual ratio	40.10%	40.80%
Total risk-based capital for capital adequacy purposes, amount	$ 6,011	$ 4,518
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	$ 7,514	$ 5,648
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	32.053%	32.84%
Total risk-based capital for capital conservation buffer, required	1.25%	0.625%
Tier 1 risk-based capital, actual amount	$ 30,095	$ 23,065
Tier 1 risk-based capital, actual ratio	40.10%	40.80%
Tier 1 risk-based capital for capital adequacy purposes, amount	$ 4,508	$ 3,389
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	$ 6,011	$ 4,518
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	34.053%	34.84%
Tier 1 risk-based capital for capital conservation buffer, required	1.25%	0.625%
Common equity tier 1 capital, actual amount	$ 30,095	$ 23,065
Common equity tier 1 capital, actual ratio	40.10%	40.80%
Common equity tier 1 capital for capital adequacy purposes, amount	$ 3,381	$ 2,541
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	$ 4,884	$ 3,671
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	35.55%	36.34%
Common equity tier 1 capital for capital conservation buffer, required	1.25%	0.625%
Tier 1 leverage ratio, actual amount	$ 30,095	$ 23,065
Tier 1 leverage ratio, actual ratio	9.62%	8.10%
Tier 1 leverage ratio for capital adequacy purposes, amount	$ 12,508	$ 11,409
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	$ 15,635	$ 14,262
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	5.624%	4.086%
Tier 1 leverage ratio for capital conservation buffer, required	1.25%	0.625%