Pension Plans (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Pension plans
Expenses recorded under the plan	$ 21,000	$ 26,000
Defined contribution 401(k) plan
Matching contributions to the plan	21,000	26,000
Excess plan
Pension plans
Fair values of pension assets	710,000		680,000
Future benefit accruals	0
Components of net periodic pension cost
Interest cost	113,000	114,000
Expected return on plan assets	(138,000)	(127,000)
Recognized net actuarial loss	24,000	20,000
Net periodic pension cost	(1,000)	7,000
Contributions to pension plans	56,000
SERP
Pension plans
Expenses recorded under the plan	15,000
Liability for pension benefits	20,000		60,000
Components of net periodic pension cost
Contributions to pension plans	55,000
Defined contribution 401(k) plan
Matching contributions to the plan	$ 15,000