Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares		3 Months Ended		9 Months Ended
	Oct. 28, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Dividend reinvestment plan, shares				38,947	44,322
Stock purchase and compensation plans, shares				686,984	588,858
Dividends to stockholders, per share	$ 0.15	$ 0.14	$ 0.13	$ 0.42	$ 0.39
Acquisition of treasury stock, shares				139,031	130,573
Preferred stock, par value per share		$ 0	$ 0	$ 0	$ 0	$ 0
Preferred stock, shares authorized		5,000,000	5,000,000	5,000,000	5,000,000	5,000,000
Preferred stock, shares issued		0	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