Employee Benefit Plans (Details 4) (Pension Plan, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Plan
Prepaid pension cost as of beginning of fiscal year	$ 671	$ 270
Net periodic pension cost for fiscal year	(1,876)	(2,099)	(2,295)
Employer contributions	2,500	2,500	2,500
Effect of curtailment	(63)
Prepaid pension asset as of end of fiscal year	$ 1,232	$ 671	$ 270