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Consolidated Statement of Changes in Stockholders' Equity (Parenthetical) - $ / shares | 3 Months Ended
--- | ---
Mar. 31, 2018 | Mar. 31, 2017
Common stock |  |
Common stock transactions: |  |
Common shares purchased and retired | 21,700 | 20,621
Common shares issued | 0 | 200
Non-vested common shares issued | 204,991 | 132,531
Non-vested common shares forfeited | 16,581 | 7,214
Stock options exercised (in shares) | 67,146 | 112,936
Shares tendered in payment of option price and income tax withholding amounts | 20,469 | 43,534
Retained earnings |  |
Common stock transactions: |  |
Common dividends (in dollars per share) | $ 0.28 | $ 0.24

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