Pension and Other Post-Retirement Benefit Plans (Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 0	$ 0
Interest cost	8,968	8,646
Expected return on plan assets	(10,264)	(11,020)
Amortization of prior service cost	0	0
Amortization of net (gain) loss	3,368	1,793
Net periodic benefit cost (gain)	2,072	(581)
Post-Retirement Healthcare Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	31	44
Interest cost	42	48
Expected return on plan assets	0	0
Amortization of prior service cost	(26)	(136)
Amortization of net (gain) loss	40	73
Net periodic benefit cost (gain)	$ 87	$ 29