Retirement Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
SERP [Member]
Components of net periodic pension cost for retirement plan
Service cost	$ 25	$ 20
Interest cost	28	31
Amortization of unrecognized gains and losses	26	20
Amortization of prior service cost	10	10
Net periodic pension cost	89	81
Directors' Retirement Plan [Member]
Components of net periodic pension cost for retirement plan
Service cost	1	1
Interest cost	7	9
Amortization of prior service cost		22
Net periodic pension cost	$ 8	$ 32