Pension and Other Post-Retirement Benefit Plans (Funded Status) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Plans [Member]
Change in benefit obligation [Roll Forward]
Obligation, beginning balance	$ 860,463	$ 772,612
Service cost	0	0	0
Interest cost	35,957	37,089	37,163
Curtailment gain	0	0
Special termination benefits	0	0
Plan amendment	0	0
Plan transfers	2,448	1,657
Benefits paid	(28,966)	(26,130)
Actuarial (gain) loss	(108,128)	75,235
Obligation, ending balance	761,774	860,463	772,612
Change in plan assets [Roll Forward]
Plan assets, beginning balance	682,553	594,697
Actual gain on plan assets	67,719	87,598
Employer contributions	27,492	24,731
Plan assets, ending balance	751,246	682,553	594,697
Funded status
Recorded liabilities - net underfunded	14,855	0
Post-Retirement Healthcare Plans [Member]
Change in benefit obligation [Roll Forward]
Obligation, beginning balance	8,781	9,275
Service cost	275	269	247
Interest cost	264	379	389
Curtailment gain	0	0
Special termination benefits	0	0
Plan amendment	0	(460)
Plan transfers	0	0
Benefits paid	(1,364)	(974)
Actuarial (gain) loss	(474)	292
Obligation, ending balance	7,482	8,781	9,275
Change in plan assets [Roll Forward]
Plan assets, beginning balance	0	0
Actual gain on plan assets	0	0
Employer contributions	1,364	974
Plan assets, ending balance	0	0	0
Funded status
Recorded liabilities - net underfunded	0	0
Other Current Liabilities [Member] | Pension Plans [Member]
Funded status
Recorded liabilities - net underfunded	(1,339)	(1,331)
Other Current Liabilities [Member] | Post-Retirement Healthcare Plans [Member]
Funded status
Recorded liabilities - net underfunded	(888)	(1,105)
Other Noncurrent Liabilities [Member] | Pension Plans [Member]
Funded status
Recorded liabilities - net underfunded	(24,044)	(176,579)
Other Noncurrent Liabilities [Member] | Post-Retirement Healthcare Plans [Member]
Funded status
Recorded liabilities - net underfunded	$ (6,594)	$ (7,676)