Employee Benefit Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Present value of future salary contribution plan benefits	$ 19,500,000	$ 16,900,000
Cash Surrender Value of Life Insurance	93,831,000	92,555,000
Post-retirement benefits payable	1,900,000	1,500,000
Postemployment benefits, period expense	2,500,000	1,800,000	1,800,000
Liabilities recorded in connection with deferred compensation plan benefits	2,900,000	2,400,000
Plan balance recorded in other liabilities	2,300,000	2,500,000
Defined contribution plan cost recognized	3,000,000	2,700,000	2,200,000
Supplemental Retirement and Deferred Compensation Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percentage eligible officers may elect, retirement plan	50.00%
Supplemental Retirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions	116,000	96,000	56,000
Plan balance recorded in other liabilities	566,000	530,000
Pension and other postretirement defined benefit plans, liabilities	$ 1,100,000	$ 532,000