CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Statement of Stockholders Equity [Abstract]
Common stock cash dividends declared, per share (in dollars per share)	$ 0.62	$ 0.62	$ 0.62
Treasury shares purchased under deferred directors' plan (in shares)	10,648	11,081	11,425
Treasury stock sold and distributed under deferred directors' plan (in shares)	30,100	21,491	16,547
Stock activity under stock compensation plans (in shares)	47,900	125,457	79,950
Issuance of common stock (in shares)	0	0	3,625,431
Issuance of shares of preferred stock at discount (in shares)	0	0	56,044
Issuance of warrant to purchase shares of common stock (in shares)	0	0	396,538
Redemption of shares of preferred stock (in shares)	0	56,044	0