Employee Benefit Plans (Details) (Pension Plan, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Plan
Benefit obligation at beginning of year	$ 40,084	$ 31,140	$ 25,395
Service cost	1,835	1,782	1,754
Interest cost	1,451	1,638	1,555
Actuarial (gain) loss	(4,006)	6,004	2,830
Benefits paid	(503)	(480)	(394)
Curtailment gain	(6,589)
Benefit obligation at end of year	32,272	40,084	31,140
Plan assets at beginning of year	24,466	22,431	17,793
Actual return on plan assets	3,661	15	2,532
Employer contributions	2,500	2,500	2,500
Benefits paid - plan	(503)	(480)	(394)
Plan assets at end of year	30,124	24,466	22,431
Funded status at end of year	$ (2,148)	$ (15,618)	$ (8,709)