Condensed Financial Statements of Greene County Bancorp, Inc., Condensed Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
INCOME [Abstract]
Other Income	$ 1,374	$ 912
OPERATING EXPENSES [Abstract]
Interest on borrowings	2,971	3,352
Other expense	3,097	3,029
Net income	24,769	30,785
Parent Company [Member]
INCOME [Abstract]
Equity in undistributed net income of subsidiaries	19,096	26,829
Dividend distributed by subsidiary	$ 8,000	$ 6,400
Investment, Issuer Affiliation [Extensible Enumeration]	us-gaap:InvestmentsInMajorityOwnedSubsidiariesMember	us-gaap:InvestmentsInMajorityOwnedSubsidiariesMember
Interest-earning deposits	$ 13	$ 6
Other Income	15	2
Total Income	27,124	33,237
OPERATING EXPENSES [Abstract]
Legal fees	98	101
Interest on borrowings	1,850	1,850
Other expense	407	501
Total operating expenses	2,355	2,452
Net income	$ 24,769	$ 30,785