Pensions and Other Postretirement Benefit Plans (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,991	$ 2,268
Interest cost	6,110	5,779
Expected return on assets	(6,763)	(6,418)
Curtailment gain	(130)
Amortization of prior service cost/(credit)	28	36
Amortization of net actuarial loss	1,756	1,924
Net periodic benefit cost	2,992	3,589
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	190	250
Interest cost	1,832	1,831
Expected return on assets
Curtailment gain
Amortization of prior service cost/(credit)	(3,366)	(3,366)
Amortization of net actuarial loss	2,114	2,504
Net periodic benefit cost	$ 770	$ 1,219