Pension and Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	$ 672	$ 763	$ 2,025	$ 2,297
Defined Benefit Plan, Interest Cost	1,111	1,256	3,344	3,772
Defined Benefit Plan, Expected Return on Plan Assets	(1,329)	(1,367)	(4,027)	(4,165)
Defined Benefit Plan, Amortization of Losses	769	862	2,389	2,620
Defined Benefit Plan, Amortization of Prior Service Cost	(25)	(25)	(76)	(76)
Defined Benefit Plan, Net Periodic Benefit Cost	1,198	1,489	3,655	4,448
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year			7,500
Defined Benefit Plan, Contributions by Employer			6,600
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	0	1	8	12
Defined Benefit Plan, Interest Cost	28	47	106	146
Defined Benefit Plan, Expected Return on Plan Assets	0	0	0	0
Defined Benefit Plan, Amortization of Losses	(30)	12	0	64
Defined Benefit Plan, Amortization of Prior Service Cost	0	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost	$ (2)	$ 60	114	$ 222
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year			500
Defined Benefit Plan, Contributions by Employer			$ 400