Pension and Postretirement Benefits other than Pensions Pension Amounts in Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	$ (82,040)	$ (73,061)	$ (71,874)	$ (55,148)
Pension Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actuarial loss	98,492	86,587
Defined Benefit Plan, Accumulated Other Comprehensive Income Net Prior Service Cost Credit, after Tax	2,217	2,432
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	$ (96,275)	$ (84,155)