Savings Plans, Pension Plans and Other Postretirement Employee Benefits Saving Plans, Pension Plans and Other Postretirement Employee Benefits (Other Amounts Recognized in Consolidated Statements of Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net amount at beginning of year	$ (140,898)
Taxes	21,424	(5,968)	(21,960)
Net amount arising during the period	33,510	(9,334)	(34,347)
Taxes	0	2,159	2,264
Net reclassifications during the period	42,178	(16)	(27,127)
Net amount at end of year	(98,720)	(140,898)
Pension Plans, Defined Benefit [Member]
Net amount at beginning of year	161,667	158,883	130,445
Net loss (gain)	(52,242)	20,180	57,220
Prior service cost (credit)	0	510	0
Taxes	20,374	(8,069)	(22,316)
Net amount arising during the period	(31,868)	12,621	34,904
Amortization of prior service (cost) credit	(779)	(770)	(684)
Amortization of actuarial loss	(19,929)	(15,356)	(9,916)
Taxes	8,076	6,289	4,134
Net reclassifications during the period	(12,632)	(9,837)	(6,466)
Net amount at end of year	117,167	161,667	158,883
Other Postretirement Benefit Plans, Defined Benefit [Member]
Net amount at beginning of year	(20,769)	(18,001)	(16,690)
Net loss (gain)	(2,692)	(4,878)	(913)
Prior service cost (credit)	0	(5,942)	(5,805)
Taxes	1,050	4,260	2,620
Net amount arising during the period	(1,642)	(6,560)	(4,098)
Amortization of prior service (cost) credit	9,708	9,343	8,536
Amortization of actuarial loss	(3,209)	(3,127)	(3,967)
Taxes	(2,535)	(2,424)	(1,782)
Net reclassifications during the period	3,964	3,792	2,787
Net amount at end of year	$ (18,447)	$ (20,769)	$ (18,001)