Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Forfeiture of restricted stock award grants shares	2,482
Restricted stock award grants, shares	39,673
Issuance of common stock, net of issuance costs,shares	894,896
Purchase of treasury stock, shares	75,162	1,298	51,052
Reissue of treasury stock, shares		7,933	6,766
Cash dividends declared, per share	$ 0.66	$ 0.66	$ 0.66
Additional Paid-In Capital [Member]
Forfeiture of restricted stock award grants shares	2,482
Restricted stock award grants, shares	39,673	52,750	48,300
Issuance of common stock, net of issuance costs,shares	834,896
Purchase of treasury stock, shares	75,162
Reissue of treasury stock, shares		7,933	6,766
Retained Earnings [Member]
Cash dividends declared, per share	$ 0.66	$ 0.66	$ 0.66
Treasury Stock [Member]
Forfeiture of restricted stock award grants shares	2,482
Restricted stock award grants, shares	39,673	52,750	48,300
Purchase of treasury stock, shares	75,162	1,298	51,052
Reissue of treasury stock, shares		7,933	6,766