Consolidated Statement of Changes in Shareholders' Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Common stock per share dividend amount	$ 2.80	$ 2.80	$ 2.80
Preferred Stock [Member]
Shares of common stock issued upon conversion of Series B preferred stock		433,144
Common Stock [Member]
Shares of common stock issued upon conversion of Series B preferred stock		433,144
Additional Paid-in Capital [Member]
Shares of common stock issued upon conversion of Series B preferred stock		433,144
Retained Earnings [Member]
Common stock per share dividend amount	$ 2.80	$ 2.80	$ 2.80
Treasury Stock [Member]
Shares of common stock issued upon conversion of Series B preferred stock		433,144