Consolidated Statements of Stockholders' Equity (Parenthetical) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Dividend reinvestment plan, shares			29,949	33,514
Stock purchase and compensation plans, shares			547,190	682,661
Dividends to stockholders, per share	$ 0.13	$ 0.13	$ 0.26	$ 0.26
Acquisition of treasury stock, shares			124,819	151,113
Preferred stock, par value per share	$ 0	$ 0	$ 0	$ 0
Preferred stock, shares authorized	5,000,000	5,000,000	5,000,000	5,000,000
Preferred stock, shares issued	0	0	0	0
Series A Preferred Stock [Member]
Preferred stock, par value per share	$ 0	$ 0	$ 0	$ 0
Preferred stock, shares authorized	300,000	300,000	300,000	300,000