Pension and Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	$ 683	$ 761	$ 1,353	$ 1,534
Defined Benefit Plan, Interest Cost	1,122	1,254	2,233	2,516
Defined Benefit Plan, Expected Return on Plan Assets	(1,354)	(1,396)	(2,698)	(2,798)
Defined Benefit Plan, Amortization of Losses	812	877	1,620	1,758
Defined Benefit Plan, Amortization of Prior Service Cost	(26)	(25)	(51)	(51)
Defined Benefit Plan, Net Periodic Benefit Cost	1,237	1,471	2,457	2,959
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year			7,500
Defined Benefit Plan, Contributions by Employer			5,000
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	4	6	8	11
Defined Benefit Plan, Interest Cost	39	49	78	99
Defined Benefit Plan, Expected Return on Plan Assets	0	0	0	0
Defined Benefit Plan, Amortization of Losses	15	26	30	52
Defined Benefit Plan, Amortization of Prior Service Cost	0	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost	$ 58	$ 81	116	$ 162
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year			500
Defined Benefit Plan, Contributions by Employer			$ 300