Consolidated Statements of Changes in Stockholders Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Common stock
Common stock transactions:
Common shares purchased and retired	20,621	1,015,389
Common shares issued	200	16,347
Non-vested common shares issued	132,531	190,239
Non-vested common shares forfeited	7,214	29,844
Stock options exercised	112,936	336,598
Shares tendered in payment of option price and income tax withholding amounts	43,534	104,643
Retained earnings
Cash dividends declared:
Common (in dollars per share)	$ 0.24	$ 0.88