Consolidated Statements of Changes in Stockholders' Equity(Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Consolidated Statements of Changes in Shareholders' Equity
Cash dividend declared, per share	$ 1.08	$ 1.08	$ 1.08
Acquisition of treasury stock, shares			9,819
Treasury shares issued to fund dividend reinvestment plan, shares		36,250	47,874
Treasury shares issued under stock option plan, shares	1,776	1,098	113
Common stock issued under dividend reinvestment plan, shares	102,201	18,154