Pension and Other Postretirement Benefits Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Pension Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	$ 5,534	$ 5,532	$ 12,059	$ 11,107
Defined Benefit Plan, Interest Cost	5,982	6,123	11,957	12,448
Defined Benefit Plan, Expected Return on Plan Assets	(5,979)	(5,910)	(11,954)	(11,835)
Defined Benefit Plan, Amortization of Gains (Losses)	6,860	5,408	13,185	10,558
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	338	340	688	690
Defined Benefit Plan, Net Periodic Benefit Cost	12,735	11,493	25,935	22,968
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	647	518	1,322	1,168
Defined Benefit Plan, Interest Cost	711	828	1,436	1,678
Defined Benefit Plan, Expected Return on Plan Assets	0	0	0	0
Defined Benefit Plan, Amortization of Gains (Losses)	422	435	897	860
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(540)	(565)	(1,090)	(1,090)
Defined Benefit Plan, Net Periodic Benefit Cost	$ 1,240	$ 1,216	$ 2,565	$ 2,616