Components of Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 510	$ 559
Interest cost	939	846
Expected return on plan assets	(948)	(827)
Amortization of transition obligation	0	0
Net amortization of prior service cost	(2)	(4)
Net amortization of net (gain) loss	190	523
Net Periodic Benefit Cost	689	1,097
Post-Retirement Health Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	13	17
Interest cost	44	43
Expected return on plan assets	0	0
Amortization of transition obligation	0	15
Net amortization of prior service cost	0	0
Net amortization of net (gain) loss	0	0
Net Periodic Benefit Cost	$ 57	$ 75