Retirement Plans (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Retirement Plans (Textual) [Abstract]
Accumulated other comprehensive loss	$ (2,206,000)	$ (2,204,000)	$ (684,000)
Deferred tax asset	1,600,000	1,598,000
Retirement Plans (Additional Textual) [Abstract]
Employee service period under ESOP	1 year
Contributions to the plan included in salary expense	1,229,000	1,084,000	1,046,000
Deferred compensation obligations	7,738,000	8,209,000
Earnings credits on deferred balances included in noninterest expense	599,000	649,000	683,000
Net actuarial loss	(3,123,000)	(3,515,000)	(218,000)
401 (k) Plan [Member]
Retirement Plans (Textual) [Abstract]
Minimum age for employees	21 years
Minimum period for employees to participate	90 days
Supplemental Employee Retirement Plan [Member]
Retirement Plans (Textual) [Abstract]
Cash values of the insurance policies purchased to fund deferred compensation obligations	50,582,000	50,403,000
Unfunded status of the supplemental retirement plans	3,806,000	3,802,000
Accumulated other comprehensive loss	2,206,000	2,204,000
Deferred tax asset	$ 1,600,000	$ 1,598,000