Cover - shares	6 Months Ended
	Dec. 31, 2024	Feb. 06, 2025
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Amendment Flag	false
Document Period End Date	Dec. 31, 2024
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	Q2
Entity Information [Line Items]
Entity Registrant Name	GREENE COUNTY BANCORP, INC.
Entity Central Index Key	0001070524
Entity File Number	0-25165
Entity Tax Identification Number	14-1809721
Entity Incorporation, State or Country Code	X1
Current Fiscal Year End Date	--06-30
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Contact Personnel [Line Items]
Entity Address, Address Line One	302 Main Street
Entity Address, City or Town	Catskill
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	12414
Entity Phone Fax Numbers [Line Items]
City Area Code	518
Local Phone Number	943-2600
Entity Listings [Line Items]
Title of 12(b) Security	Common Stock, $0.10 par value
Trading Symbol	GCBC
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		17,026,828