Retirement Benefits Change in Net Benefit Obligation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Qualified Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of period	$ 573,317	$ 616,290
Service cost	(4,512)	(19,285)
Interest cost	7,055	24,754
Amendments	0	0
Actuarial loss/(gain)	0	(48,559)
Benefits paid	(10,001)	(38,453)
Medicare part D subsidiary received	0	0
Benefit obligation at end of period	574,883	573,317
SERP Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of period	47,279	51,795
Service cost	(261)	(1,498)
Interest cost	577	2,045
Amendments	0	478
Actuarial loss/(gain)	0	(1,687)
Benefits paid	(460)	(6,850)
Medicare part D subsidiary received	0	0
Benefit obligation at end of period	47,657	47,279
Other Benefit [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of period	14,939	17,672
Service cost	(29)	(134)
Interest cost	183	664
Amendments	0	0
Actuarial loss/(gain)	0	(2,240)
Benefits paid	(391)	(1,536)
Medicare part D subsidiary received	42	245
Benefit obligation at end of period	$ 14,802	$ 14,939