Pensions and Other Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]
Service cost	$ 453	$ 361	$ 1,356	$ 1,103
Interest cost	301	439	904	1,341
Expected return on plan assets	(249)	(326)	(748)	(995)
Amortization of transition asset	22	21	66	65
Amortization of prior service cost	21	(2)	59	(5)
Amortization of actuarial loss	181	135	548	405
Net periodic pension cost	$ 643	$ 590	1,935	$ 1,794
Contributions by employer			$ 1,000