Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Projected benefit obligation:
Balance, January 1	$ 53,972	$ 43,337
Service cost	2,799	2,073
Interest cost	2,570	2,423
Actuarial loss	9,063	7,357
Benefits paid	(1,317)	(1,218)
Balance, December 31	67,087	53,972
Plan assets:
Fair value, January 1	53,895	45,427
Actual return	6,556	686
Employer contribution	2,250	9,000
Benefits paid	(1,317)	(1,218)
Fair value, December 31	61,384	53,895
Funded status:
Accrued pension asset (liability)	$ (5,703)	$ (77)