Shareholders' Equity (Details) (USD $)	3 Months Ended			3 Months Ended				3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Aug. 21, 2007	Mar. 31, 2013 Common Stock [Member]	Dec. 31, 2012 Common Stock [Member]	Mar. 31, 2012 Common Stock [Member]	Dec. 31, 2011 Common Stock [Member]	Mar. 31, 2013 Tri countries bank [Member]	Mar. 31, 2012 Tri countries bank [Member]
Shareholders' Equity (Textual) [Abstract]
Cash dividends received								$ 1,700,000	$ 1,625,000
Company's common stock in lieu of cash to exercise options to purchase shares	20,000			15,647
Shareholders Equity (Additional Textual) [Abstract]
Shareholder Rights Plan	Jun. 25, 2001
Amendment date of Rights Plan	Jul. 08, 2011
Extended maturity date of Rights Plan	Jul. 10, 2021
Percentage of restriction on acquiring outstanding common stock by person or group	15.00%
Portion of market value to acquire common stock or shares	one-half of market value
Initial exercise price of rights	49.00
Redemption price of rights	0.01
Preferred Stock dividend declared for each common share held	1
Common stock, shares outstanding	16,005,191	16,000,838	15,814,662	16,005,191	16,000,838	15,978,958	15,978,958
Repurchase of common stock			500,000
Stock repurchase plan percentage of common stock			3.20%
Repurchased shares outstanding	166,600