Consolidated Statement of Changes in Shareholders' Equity (Unaudited) (Parenthetical)	6 Months Ended
	Jun. 30, 2018 $ / shares shares
Cash dividends per share | $ / shares	$ 0.68
Common stock options exercised, shares	42,089
Common Stock [Member]
Purchase of treasury stock, shares	973,346
Grant of restricted stock, shares	97,004
Forfeiture of restricted stock, shares	2,853
Common stock options exercised, shares	42,089
Retained Earnings [Member]
Cash dividends per share | $ / shares	$ 0.68
Treasury Stock [Member]
Purchase of treasury stock, shares	973,346