Components of Net Periodic Pension Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Net pension cost of plans
Service cost		$ 86	$ 100	$ 171
Interest cost	1,916	1,809	3,855	3,618
Expected return on plan assets	(2,109)	(1,846)	(4,218)	(3,691)
Recognized actuarial loss	921	1,672	1,842	3,344
Net periodic benefit cost	$ 728	$ 1,721	$ 1,579	$ 3,442