Consolidated Statements of Changes in Stockholders' Equity Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Statement of Stockholders' Equity [Abstract]
Dividends on perferred stock (in dollars per share)	$ 850	$ 407	$ 455
Dividends on common stock (in dollars per share)	$ 0.42	$ 0.40	$ 0.38
Issuance of preferred stock (in shares)	1,650	3,850	0
Issuance of common shares pursuant to the Dividend Reinvestment Plan (in shares)	53,944	44,521	38,494
Issuance of common shares pursuant to the Deferred Compensation Plan (in shares)	6,048	5,920	4,766
Issuance of common shares pursuant to the First Retirement & Savings Plan (in shares)	19,366	9,693	19,414
Issuance of restricted common shares pursuant to the 2007 Stock Incentive Plan (in shares)	5,320	4,436	0
Purchase of treasury shares (in shares)	165,117	128,073	136,380
Issuance of common shares pursuant to the exercise of stock options (in shares)	44,763	11,392	49,500