Condensed Financial Statements of Greene County Bancorp, Inc., Condensed Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
OPERATING EXPENSES [Abstract]
Other	$ 2,244	$ 2,134
Net income	8,963	7,189
Parent Company [Member]
INCOME [Abstract]
Equity in undistributed net income of subsidiaries	5,239	7,491
Dividend distributed by subsidiary	4,004	4
Interest-earning deposits	6	5
Total income	9,249	7,500
OPERATING EXPENSES [Abstract]
Legal Fees	66	201
Other	220	110
Total operating expenses	286	311
Net income	$ 8,963	$ 7,189