Use of Estimates	6 Months Ended
Dec. 31, 2012
Use of Estimates [Abstract]
Use of Estimates	(3) Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Material estimates that are particularly susceptible to significant change in the near term relate to the determination of the allowance for loan losses and the assessment of other-than-temporary security impairment. While management uses available information to recognize losses on loans, future additions to the allowance for loan losses (the "Allowance") may be necessary, based on changes in economic conditions, asset quality or other factors. In addition, various regulatory authorities, as an integral part of their examination process, periodically review the Allowance. Such authorities may require the Company to recognize additions to the Allowance based on their judgments of information available to them at the time of their examination. Greene County Bancorp, Inc. makes an assessment to determine whether there have been any events or economic circumstances to indicate that a security on which there is an unrealized loss is impaired on an other-than-temporary basis. The Company considers many factors including the severity and duration of the impairment; the intent and ability of the Company to hold the security for a period of time sufficient for a recovery in value; recent events specific to the issuer or industry; and for debt securities, intent to sell the security, whether it is more likely than not we will be required to sell the security before recovery, whether loss of the entire amortized cost is expected, external credit ratings and recent downgrades. Securities on which there is an unrealized loss that is deemed to be other-than-temporary are written down to fair value.

(3) Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Material estimates that are particularly susceptible to significant change in the near term relate to the determination of the allowance for loan losses and the assessment of other-than-temporary security impairment.

While management uses available information to recognize losses on loans, future additions to the allowance for loan losses (the "Allowance") may be necessary, based on changes in economic conditions, asset quality or other factors. In addition, various regulatory authorities, as an integral part of their examination process, periodically review the Allowance. Such authorities may require the Company to recognize additions to the Allowance based on their judgments of information available to them at the time of their examination.

Greene County Bancorp, Inc. makes an assessment to determine whether there have been any events or economic circumstances to indicate that a security on which there is an unrealized loss is impaired on an other-than-temporary basis. The Company considers many factors including the severity and duration of the impairment; the intent and ability of the Company to hold the security for a period of time sufficient for a recovery in value; recent events specific to the issuer or industry; and for debt securities, intent to sell the security, whether it is more likely than not we will be required to sell the security before recovery, whether loss of the entire amortized cost is expected, external credit ratings and recent downgrades. Securities on which there is an unrealized loss that is deemed to be other-than-temporary are written down to fair value.