Pension and Other Post-Retirement Benefit Plans (Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	8,968	8,646	26,904	25,938
Expected return on plan assets	10,264	11,020	(30,792)	(33,060)
Amortization of prior service cost	0	0	0	0
Amortization of net (gain) loss	(3,368)	(1,793)	10,104	5,379
Net periodic benefit cost (gain)	2,072	(581)	6,216	(1,743)
Post-Retirement Healthcare Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	31	44	93	132
Interest cost	42	48	126	144
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(26)	(136)	(78)	(408)
Amortization of net (gain) loss	40	73	120	(219)
Net periodic benefit cost (gain)	$ 87	$ 29	$ 261	$ 87