Pension and Other Postretirement Benefits Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Pension Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	$ 6,525	$ 5,575
Defined Benefit Plan, Interest Cost	5,975	6,325
Defined Benefit Plan, Expected Return on Plan Assets	(5,975)	(5,925)
Defined Benefit Plan, Amortization of Gains (Losses)	6,325	5,150
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	350	350
Defined Benefit Plan, Net Periodic Benefit Cost	13,200	11,475
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	675	650
Defined Benefit Plan, Interest Cost	725	850
Defined Benefit Plan, Expected Return on Plan Assets	0	0
Defined Benefit Plan, Amortization of Gains (Losses)	475	425
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(550)	(525)
Defined Benefit Plan, Net Periodic Benefit Cost	$ 1,325	$ 1,400