Pension Plans (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Pension Plans
Expected long-term rate of return on plan assets (as a percent)			8.00%	8.50%
Components of net periodic pension cost
Service cost		$ 58,000		$ 134,000
Interest cost	113,000	122,000	227,000	250,000
Expected return on plan assets	(127,000)	(119,000)	(254,000)	(253,000)
Curtailment loss		45,000		45,000
Recognized net actuarial loss	20,000	45,000	40,000	84,000
Net amortization		4,000		10,000
Net periodic pension cost	6,000	155,000	13,000	270,000
Expected contributions to pension plans in 2012	200,000		200,000
Contributions to pension plans	$ 45,000	$ 68,000	$ 101,000	$ 129,000