Defined Benefit Pension Plan Net Periodic Pension Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 294	$ 170	$ 550	$ 340
Interest cost on projected benefit obligation	220	209	442	418
Expected return on plan assets	(237)	(219)	(474)	(438)
Amortization of prior service cost	2	2	4	4
Amortization of net loss	147	46	294	92
Net periodic benefit cost	$ 426	$ 208	$ 816	$ 416