Pension and Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	$ 670	$ 773
Defined Benefit Plan, Interest Cost	1,111	1,262
Defined Benefit Plan, Expected Return on Plan Assets	(1,344)	(1,402)
Defined Benefit Plan, Amortization of Losses	808	881
Defined Benefit Plan, Amortization of Prior Service Cost	(25)	(26)
Defined Benefit Plan, Net Periodic Benefit Cost	1,220	1,488
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	7,500
Defined Benefit Plan, Contributions by Employer	3,600
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	4	5
Defined Benefit Plan, Interest Cost	39	50
Defined Benefit Plan, Expected Return on Plan Assets	0	0
Defined Benefit Plan, Amortization of Losses	15	26
Defined Benefit Plan, Amortization of Prior Service Cost	0	0
Defined Benefit Plan, Net Periodic Benefit Cost	58	$ 81
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	500
Defined Benefit Plan, Contributions by Employer	$ 200