Pension and Other Post-Retirement Benefit Plans (Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 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	17,936	17,292
Expected return on plan assets	10,264	11,020	(20,528)	(22,040)
Amortization of prior service cost	0	0	0	0
Amortization of net (gain) loss	(3,368)	(1,793)	6,736	3,586
Net periodic benefit cost (gain)	2,072	(581)	4,144	(1,162)
Post-Retirement Healthcare Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	31	44	62	88
Interest cost	42	48	84	96
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(26)	(136)	(52)	(272)
Amortization of net (gain) loss	40	73	80	(146)
Net periodic benefit cost (gain)	$ 87	$ 29	$ 174	$ 58