Earnings Per Share and Restricted Stock	3 Months Ended
Mar. 31, 2020
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 8,477,642 and 7,046,671 weighted average shares of common stock outstanding for the three months ended March 31, 2020 and 2019, 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 March 31, 2020, 25,945 shares were issued under this plan, of which 23,730 were fully vested and 2,215 shares vested during the quarter. 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, shareholders 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 March 31, 2020, 16,115 shares were issued under this plan, of which 5,372 were fully vested, 5,372 vested during the quarter, and the remaining 5,371 will vest over the next year. 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. $262,000 and $126,000 of compensation expenses related to the grants were recognized during the three months ended March 31, 2020 and 2019, 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 8,477,642 and 7,046,671 weighted average shares of common stock outstanding for the three months ended March 31, 2020 and 2019, 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 March 31, 2020, 25,945 shares were issued under this plan, of which 23,730 were fully vested and 2,215 shares vested during the quarter. 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, shareholders 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 March 31, 2020, 16,115 shares were issued under this plan, of which 5,372 were fully vested, 5,372 vested during the quarter, and the remaining 5,371 will vest over the next year. 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. $262,000 and $126,000 of compensation expenses related to the grants were recognized during the three months ended March 31, 2020 and 2019, respectively.