Retirement Plans (Net Periodic Benefit Cost) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension settlement costs	$ 40,309		$ 40,309
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	12,141	11,782	37,809	32,766
Interest cost on projected benefit obligation	18,827	19,204	56,587	58,520
Expected return on plan assets	(23,585)	(23,655)	(72,765)	(71,832)
Amortization of prior service cost/(credit)	2	(50)	6	(150)
Amortization of unrecognized loss	10,798	6,845	30,942	22,418
Net periodic pension benefit cost	18,183	14,126	52,579	41,722
Pension settlement costs	40,309		40,309
Total periodic benefit cost	58,492	14,126	92,888	41,722
Postretirement Benefits Other Than Pensions (OPEB) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	3,088	2,999	9,446	8,109
Interest cost on projected benefit obligation	4,181	4,462	13,061	13,382
Expected return on plan assets	(25)	(20)	(111)	(130)
Amortization of prior service cost/(credit)	(1,526)	(2,545)	(4,576)	(7,551)
Amortization of unrecognized loss	1,695	1,831	6,151	5,653
Total periodic benefit cost	$ 7,413	$ 6,727	$ 23,971	$ 19,463