Pension and Other Post-Retirement Benefit Plans (Net Periodic Benefit Costs) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 0	$ 0	$ 2,286
Interest cost	37,089	37,163	36,678
Expected return on plan assets	(39,882)	(39,027)	(35,600)
Amortization of prior service cost	0	0	0
Amortization of net (gain) loss	10,681	2,700	2,069
Net periodic benefit cost	7,888	836	5,433
Post-Retirement Healthcare Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	269	247	341
Interest cost	379	389	800
Expected return on plan assets	0	0	0
Amortization of prior service cost	433	529	364
Amortization of net (gain) loss	(5,552)	(5,552)	(4,167)
Net periodic benefit cost	$ (4,471)	$ (4,387)	$ (2,662)