Components of Net Periodic 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
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 510	$ 559	$ 1,020	$ 1,119
Interest cost	939	846	1,878	1,692
Expected return on plan assets	(948)	(827)	(1,897)	(1,655)
Amortization of transition obligation	0	0		0
Net amortization of prior service cost	(2)	(4)	(5)	(8)
Net amortization of net (gain) loss	190	523	379	1,046
Net Periodic Benefit Cost	689	1,097	1,375	2,194
Post-Retirement Health Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	13	17	26	34
Interest cost	44	43	87	87
Expected return on plan assets	0	0		0
Amortization of transition obligation	0	15		30
Net amortization of prior service cost	0	0		0
Net amortization of net (gain) loss	0	0	(1)	0
Net Periodic Benefit Cost	$ 57	$ 75	$ 112	$ 151