Pension Plan (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Components of net periodic pension cost
Service cost	$ 286	$ 290	$ 858	$ 871
Interest cost	1,165	1,262	3,495	3,785
Expected return on assets	(1,825)	(1,642)	(5,476)	(4,925)
Recognized actuarial loss	1,055	607	3,165	1,821
Net periodic pension cost	$ 681	$ 517	$ 2,042	$ 1,552