Capital Stock and Treasury Stock	9 Months Ended
Sep. 30, 2018
Equity [Abstract]
Treasury Stock	Capital Stock and Treasury Stock On June 11, 2018, our stockholders approved an increase in the number of authorized shares of our common stock from 200,000,000 to 400,000,000. Accordingly, on June 11, 2018 we filed a Certificate of Amendment to our Amended and Restated Certificate of Incorporation increasing the total number of shares of capital which we have authority to issue to 410,000,000 shares, consisting of 400,000,000 shares of common stock, par value $0.01 per share, and 10,000,000 shares of preferred stock, par value of $0.01 per share. On October 17, 2016, our Board of Directors authorized the repurchase by us of up to an aggregate of $300.0 million of our common stock by various means from time to time through and including December 31, 2021, of which we had approximately $129.4 million remaining under this authorization for the repurchase of our common stock at September 30, 2018. We did not repurchase any shares of our common stock under this authorization during the nine months ended September 30, 2018. During the first nine months of 2018, we issued 339,972 treasury shares which had an average cost of $3.12 per share for restricted stock units that vested during the period. In accordance with the Silgan Holdings Inc. Amended and Restated 2004 Stock Incentive Plan, we repurchased 107,420 shares of our common stock at an average cost of $28.46 to satisfy minimum employee withholding tax requirements resulting from the vesting of such restricted stock units. We account for treasury shares using the first-in, first-out (FIFO) cost method. As of September 30, 2018, 64,494,600 shares of our common stock were held in treasury.

Capital Stock and Treasury Stock

On June 11, 2018, our stockholders approved an increase in the number of authorized shares of our common stock from 200,000,000 to 400,000,000. Accordingly, on June 11, 2018 we filed a Certificate of Amendment to our Amended and Restated Certificate of Incorporation increasing the total number of shares of capital which we have authority to issue to 410,000,000 shares, consisting of 400,000,000 shares of common stock, par value $0.01 per share, and 10,000,000 shares of preferred stock, par value of $0.01 per share.

On October 17, 2016, our Board of Directors authorized the repurchase by us of up to an aggregate of $300.0 million of our common stock by various means from time to time through and including December 31, 2021, of which we had approximately $129.4 million remaining under this authorization for the repurchase of our common stock at September 30, 2018. We did not repurchase any shares of our common stock under this authorization during the nine months ended September 30, 2018.

During the first nine months of 2018, we issued 339,972 treasury shares which had an average cost of $3.12 per share for restricted stock units that vested during the period. In accordance with the Silgan Holdings Inc. Amended and Restated 2004 Stock Incentive Plan, we repurchased 107,420 shares of our common stock at an average cost of $28.46 to satisfy minimum employee withholding tax requirements resulting from the vesting of such restricted stock units.

We account for treasury shares using the first-in, first-out (FIFO) cost method. As of September 30, 2018, 64,494,600 shares of our common stock were held in treasury.