Employee Benefit Plans (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Components of net periodic benefit cost [Abstract]
Employer contribution to 401 (k) defined contribution plan	$ 55,000	$ 45,000	$ 201,000	$ 193,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized under restricted stock plan (in shares)	100,000		100,000
Number of restricted stock available for grant (in shares)	64,158		64,158
Restricted stock activity [Roll Forward]
Outstanding, beginning of period (in shares)	7,187	7,466	7,172	8,646
Granted (in shares)	0	0	3,598	3,027
Forfeited (in shares)	(7)	0	(7)	(55)
Vested (in shares)	0	0	(3,583)	(4,152)
Outstanding, end of period (in shares)	7,180	7,466	7,180	7,466
Weighted average market price [Roll Forward]
Outstanding, beginning of period (in dollars per share)	$ 48.28	$ 41.89	$ 42.02	$ 35.51
Granted (in dollars per share)	$ 0	$ 0	$ 52.82	$ 48.21
Forfeited (in dollars per share)	$ 37.10	$ 0	$ 37.10	$ 37.10
Vested (in dollars per share)	$ 0	$ 0	$ 40.30	$ 33.26
Outstanding, end of period (in dollars per share)	$ 48.29	$ 41.89	$ 48.29	$ 41.89
Share-based compensation expense	42,000	39,000	115,000	117,000
Directors [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Deferred interest expense	4,000	5,000	15,000	12,000
Pension Plan [Member]
Components of net periodic benefit cost [Abstract]
Service cost	77,000	81,000	230,000	258,000
Interest cost	104,000	89,000	311,000	274,000
Expected return on plan assets	(197,000)	(165,000)	(590,000)	(508,000)
Net amortization and deferral	13,000	66,000	38,000	194,000
Net periodic benefit cost (return)	(3,000)	71,000	(11,000)	218,000
Employer contribution to pension plan			300,000
Supplemental Executive Retirement Plans [Member]
Components of net periodic benefit cost [Abstract]
Obligation included in other liabilities	1,160,000		1,160,000		1,046,000
Cost recognized	38,000	37,000	114,000	109,000
Deferred Compensation Plan [Member]
Components of net periodic benefit cost [Abstract]
Obligation included in other liabilities	$ 963,000		$ 963,000		$ 981,000