Pension and Other Postretirement Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	May 31, 2015
Components of Net Periodic Benefit Cost [Abstract]
Defined benefit plans employer contributions toward sponsored pension plans			$ 3,500
Anticipated contribution during current fiscal year			200
Aggregate contribution towards sponsored pension plans			3,700
Reduction in post-retirement benefit liability due to remeasurement					$ (17,900)
Pension Benefits [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost-benefits earned during the period	$ 176	$ 170	532	$ 526
Interest cost on projected benefit obligation	1,855	2,297	5,593	7,021
Expected return on plan assets	(2,710)	(2,697)	(8,172)	(8,254)
Amortization of prior service (credit) cost	11	11	33	33
Amortization of loss	179	304	541	935
Total benefit cost charged (credited) to income	(489)	85	(1,473)	261
Other Benefits [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost-benefits earned during the period	65	95	200	294
Interest cost on projected benefit obligation	469	635	1,410	2,197
Expected return on plan assets	0	0	0	0
Amortization of prior service (credit) cost	(322)	(227)	(965)	(312)
Amortization of loss	103	118	314	370
Total benefit cost charged (credited) to income	$ 315	$ 621	$ 959	$ 2,549