Earnings Per Share and Restricted Stock	6 Months Ended
Jun. 30, 2019
Earnings Per Share [Abstract]
Earnings Per Share and Restricted Stock	Earnings Per Share and Restricted Stock The Corporation has a simple capital structure. Basic earnings per share of common stock is computed based on 7,049,857 and 7,030,441 weighted average shares of common stock outstanding for the six months ended June 30, 2019 and 2018, respectively, and 7,053,008 and 7,035,237 for the three months ended June 30, 2019 and 2018, respectively. All outstanding unvested restricted stock awards that contain rights to nonforfeitable dividends are considered participating securities for this calculation. The Corporation has no instruments that would create dilutive earnings per share. The ACNB Corporation 2009 Restricted Stock Plan expired by its own terms after 10 years on February 24, 2019. The purpose of this plan was to provide employees and directors of the Bank who have responsibility for its growth with additional incentives by allowing them to acquire ownership in the Corporation and, thereby, encouraging them to contribute to the organization’s success. As of June 30, 2019, 25,945 shares were issued under this plan, of which 23,725 were fully vested, no shares vested during the quarter, and the remaining 2,220 will vest over the next year. No further shares may be issued under this restricted stock plan. The Corporation’s Registration Statement under the Securities Act of 1933 on Form S-8 for the ACNB Corporation 2009 Restricted Stock Plan was filed with the Securities and Exchange Commission on January 4, 2013. Post-Effective Amendment No. 1 to this Form S-8 was filed with the Commission on March 8, 2019, effectively transferring the 174,055 authorized, but not issued, shares under the ACNB Corporation 2009 Restricted Stock Plan to the ACNB Corporation 2018 Omnibus Stock Incentive Plan. On May 1, 2018, stockholders approved and ratified the ACNB Corporation 2018 Omnibus Stock Incentive Plan, effective as of March 20, 2018, in which awards shall not exceed, in the aggregate, 400,000 shares of common stock, plus any shares that are authorized, but not issued, under the ACNB Corporation 2009 Restricted Stock Plan. As of June 30, 2019, 16,115 shares were issued under this plan, of which 5,372 vested during the quarter, and the remaining 10,743 will vest over the next two years. The Corporation’s Registration Statement under the Securities Act of 1933 on Form S-8 for the ACNB Corporation 2018 Omnibus Stock Incentive Plan was filed with the Securities and Exchange Commission on March 8, 2019. In addition, on March 8, 2019, the Corporation filed Post-Effective Amendment No. 1 to the Registration Statement on Form S-8 for the ACNB Corporation 2009 Restricted Stock Plan to add the ACNB Corporation 2018 Omnibus Stock Incentive Plan to the registration statement. Plan expense is recognized over the vesting period of the stock issued under both plans. $196,000 and $0 of compensation expenses related to the grants were recognized during the three months ended June 30, 2019 and 2018, respectively. $322,000 and $186,000 of compensation expenses related to the grants were recognized during the six months ended June 30, 2019 and 2018, respectively.

Earnings Per Share and Restricted Stock

The Corporation has a simple capital structure. Basic earnings per share of common stock is computed based on 7,049,857 and 7,030,441 weighted average shares of common stock outstanding for the six months ended June 30, 2019 and 2018, respectively, and 7,053,008 and 7,035,237 for the three months ended June 30, 2019 and 2018, respectively. All outstanding unvested restricted stock awards that contain rights to nonforfeitable dividends are considered participating securities for this calculation. The Corporation has no instruments that would create dilutive earnings per share.

The ACNB Corporation 2009 Restricted Stock Plan expired by its own terms after 10 years on February 24, 2019. The purpose of this plan was to provide employees and directors of the Bank who have responsibility for its growth with additional incentives by allowing them to acquire ownership in the Corporation and, thereby, encouraging them to contribute to the organization’s success. As of June 30, 2019, 25,945 shares were issued under this plan, of which 23,725 were fully vested, no shares vested during the quarter, and the remaining 2,220 will vest over the next year. No further shares may be issued under this restricted stock plan. The Corporation’s Registration Statement under the Securities Act of 1933 on Form S-8 for the ACNB Corporation 2009 Restricted Stock Plan was filed with the Securities and Exchange Commission on January 4, 2013. Post-Effective Amendment No. 1 to this Form S-8 was filed with the Commission on March 8, 2019, effectively transferring the 174,055 authorized, but not issued, shares under the ACNB Corporation 2009 Restricted Stock Plan to the ACNB Corporation 2018 Omnibus Stock Incentive Plan.

On May 1, 2018, stockholders approved and ratified the ACNB Corporation 2018 Omnibus Stock Incentive Plan, effective as of March 20, 2018, in which awards shall not exceed, in the aggregate, 400,000 shares of common stock, plus any shares that are authorized, but not issued, under the ACNB Corporation 2009 Restricted Stock Plan. As of June 30, 2019, 16,115 shares were issued under this plan, of which 5,372 vested during the quarter, and the remaining 10,743 will vest over the next two years. The Corporation’s Registration Statement under the Securities Act of 1933 on Form S-8 for the ACNB Corporation 2018 Omnibus Stock Incentive Plan was filed with the Securities and Exchange Commission on March 8, 2019. In addition, on March 8, 2019, the Corporation filed Post-Effective Amendment No. 1 to the Registration Statement on Form S-8 for the ACNB Corporation 2009 Restricted Stock Plan to add the ACNB Corporation 2018 Omnibus Stock Incentive Plan to the registration statement.

Plan expense is recognized over the vesting period of the stock issued under both plans. $196,000 and $0 of compensation expenses related to the grants were recognized during the three months ended June 30, 2019 and 2018, respectively. $322,000 and $186,000 of compensation expenses related to the grants were recognized during the six months ended June 30, 2019 and 2018, respectively.