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 Stockholders' Equity [Abstract]
Dividends on preferred stock (in dollars per share)	$ 407	$ 455	$ 370
Dividends on common stock (in dollars per share)	$ 0.40	$ 0.38	$ 0.38
Issuance of preferred stock (in shares)	3,850	0	4,927
Issuance of common shares pursuant to the Dividend Reinvestment Plan (in shares)	44,521	38,494	44,661
Issuance of common shares pursuant to the Deferred Compensation Plan (in shares)	5,920	4,766	9,916
Issuance of common shares pursuant to the First Retirement & Savings Plan (in shares)	9,693	19,404	19,000
Issuance of restricted common shares pursuant to the 2007 Stock Incentive Plan (in shares)	4,436	0	0
Purchase of treasury shares (in shares)	128,073	136,380	160,803
Issuance of common shares pursuant to the exercise of stock options (in shares)	11,392	49,500	37,266