Employee Benefit Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Percentage eligible officers may elect, retirement plan	50.00%
Present value of future salary contribution plan benefits	$ 16,900,000	$ 16,300,000
Cash Surrender Value of Life Insurance	92,555,000	90,161,000
Post-retirement benefits payable	1,500,000	1,400,000
Postemployment benefits, period expense	1,800,000	1,800,000	1,800,000
Liabilities recorded in connection with deferred compensation plan benefits	1,300,000	1,500,000
Plan balance recorded in other liabilities	2,500,000	3,000,000
Defined contribution plan cost recognized	2,700,000	2,200,000	2,100,000
Supplemental Retirement Plan [Member]
Contributions	96,000	56,000	6,000
Pension and other postretirement defined benefit plans, liabilities	530,000	387,000
Deferred Compensation Plan [Member]
Pension and other postretirement defined benefit plans, liabilities	$ 532,000	$ 300,000