Pension and Other Post-Retirement Benefit Plans (Net Periodic Benefit Costs) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 0	$ 0
Interest cost	8,989	9,272
Expected return on plan assets	(11,498)	(9,970)
Amortization of prior service cost	0	0
Amortization of net (gain) loss	3,074	2,670
Net periodic benefit cost (benefit)	565	1,972
Post-Retirement Healthcare Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	69	67
Interest cost	66	95
Expected return on plan assets	0	0
Amortization of prior service cost	105	(1,388)
Amortization of net (gain) loss	(1,414)	108
Net periodic benefit cost (benefit)	$ (1,174)	$ (1,118)