Pension and Other Post-Retirement Benefit Plans (Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	8,646	9,879	25,938	29,637
Expected return on plan assets	(11,020)	(11,528)	(33,060)	(34,584)
Amortization of prior service cost	0	0	0	0
Amortization of net (gain) loss	1,793	(1)	5,379	(2)
Net periodic benefit cost (gain)	(581)	(1,650)	(1,743)	(4,949)
Post-Retirement Healthcare Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	44	60	132	180
Interest cost	48	71	144	213
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(136)	(872)	(408)	(2,616)
Amortization of net (gain) loss	73	80	219	240
Net periodic benefit cost (gain)	$ 29	$ (661)	$ 87	$ (1,983)