CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) (USD $)
3 Months Ended
Mar. 31, 2012
Mar. 31, 2011
Statement of Stockholders' Equity [Abstract]    
Cash dividends per share $ 0.36 $ 0.34
Exercise of stock options and related tax benefit, shares (30,976) 16,155
Shares issued for dividend reinvestment plan, shares 17,383 12,751
Shares issued for employee stock ownership plan, shares 25,655 25,139
Directors deferred compensation plan, shares 1,672 3,625
Forfeiture of restricted shares 200 110