Components of Net Periodic Pension Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Net pension cost of plans
Service cost	$ 100	$ 86
Interest cost	1,939	1,809
Expected return on plan assets	(2,109)	(1,846)
Amortization of prior service cost	0	0
Recognized actuarial loss	921	1,672
Net periodic benefit cost	$ 851	$ 1,721