Condensed Financial Statements of Greene County Bancorp, Inc. - Condensed Statements of Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jun. 30, 2014		Jun. 30, 2013
Condensed Financial Statements, Captions [Line Items]
Net Income	$ 6,528		$ 6,371
Other comprehensive (loss) income [Abstract]
Unrealized holding (losses) gains on available for sale securities, net of income taxes of ($327) and ($526), respectively	(518)		(833)
Reclassification adjustment for gain on sale of securities realized in net income net of income taxes of $- and ($4) respectively	0	[1]	(6)	[1]
Accretion of unrealized loss on securities transferred to held to maturity,net of income taxes of $175 and $13, respectively	277	[2]	20	[2]
Pension actuarial loss, net of income taxes of ($37) and ($65)	(59)	[3]	(104)	[3]
Total other comprehensive loss, net of taxes	(300)		(923)
Comprehensive income	6,228		5,448
Income taxes, unrealized holding gain (losses) on available for sale securities	(327)		(526)
Income taxes, reclassification adjustment for gain on securities realized in net income	0		(4)
Income taxes, accretion of unrealized loss on securities transferred to held-to-maturity	175		13
Income taxes, pension actuarial gain	(37)		(65)
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net Income	6,528		6,371
Other comprehensive (loss) income [Abstract]
Unrealized holding (losses) gains on available for sale securities, net of income taxes of ($327) and ($526), respectively	(518)		(833)
Reclassification adjustment for gain on sale of securities realized in net income net of income taxes of $- and ($4) respectively	0	[1]	(6)	[1]
Accretion of unrealized loss on securities transferred to held to maturity,net of income taxes of $175 and $13, respectively	277	[4]	20	[4]
Pension actuarial loss, net of income taxes of ($37) and ($65)	(59)	[3]	(104)	[3]
Total other comprehensive loss, net of taxes	(300)		(923)
Comprehensive income	6,228		5,448
Income taxes, unrealized holding gain (losses) on available for sale securities	(327)		(526)
Income taxes, reclassification adjustment for gain on securities realized in net income	0		(4)
Income taxes, accretion of unrealized loss on securities transferred to held-to-maturity	175		13
Income taxes, pension actuarial gain	$ (37)		$ (65)

[1] Amounts are included in net gain on sale of available for sale securities on the Consolidated Statements of Income in total non-interest income.

[2] The accretion of the unrealized holding losses in accumulated other comprehensive income (loss) at the date of transfer partially offsets the amortization of the difference between the par value and fair value of the investment securities at the date of transfer, and is an adjustment of interest income.

[3] These accumulated other comprehensive income components are included in the computation of net periodic benefit cost and are included in salaries and employee benefit expense within noninterest expense (see Note 9 for additional details).

[4] The accretion of the unrealized holding losses in accumulated other comprehensive income at the date of transfer partially offsets the amortization of the difference between the par value and fair value of the investment securities at the date of transfer, and is an adjustment of interest income.