Retirement Plan (Tables)

9 Months Ended

Sep. 30, 2012

Retirement Plan [Abstract]

Net periodic defined benefit pension expense

	Three Months Ended						Nine Months Ended
	September 30, 2012			September 30, 2011			September 30, 2012			September 30, 2011
Service cost	$	666		$	545		$	1,999		$	1,635
Interest cost		555			563			1,664			1,688
Expected return on plan assets		(590	)		(560	)		(1,771	)		(1,680	)
Amortization of prior service cost		406			244			1,220			732
Net periodic benefit expense	$	1,037		$	792		$	3,112		$	2,375