Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Defined Benefits Plan Estimated Future Employer Contributions In Next Fiscal Year					$ 1,800
Post-Retirement Health Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefits Plan Estimated Future Employer Contributions In Next Fiscal Year					$ 247
Service cost	$ 16	$ 13	$ 32	$ 26
Interest cost	43	44	87	88
Expected return on plan assets	0	0	0	0
Amortization of transition obligation	0	0	0	0
Net amortization of prior service cost	0	0	0	0
Net amortization of net (gain) loss	0	0	0	0
Net Periodic Benefit Cost	59	57	119	114
Defined Benefit Plan, Contributions by Employer			110
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	538	510	1,076	1,020
Interest cost	879	939	1,758	1,878
Expected return on plan assets	(863)	(948)	(1,726)	(1,896)
Amortization of transition obligation	0	0	0	0
Net amortization of prior service cost	0	(2)	0	(4)
Net amortization of net (gain) loss	1,185	190	2,370	380
Net Periodic Benefit Cost	$ 1,739	$ 689	3,478	$ 1,378
Defined Benefit Plan, Contributions by Employer			$ 554