Employee Benefit Plans Amounts Recognized in Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax
Unrecognized prior service cost	$ 130	$ 130
Unrecognized net loss/(gain)	19,430	17,280
Total accumulated other comprehensive income (loss) recognized at December 31	19,560	17,410
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax
Unrecognized prior service cost	0	(1,530)
Unrecognized net loss/(gain)	(570)	(680)
Total accumulated other comprehensive income (loss) recognized at December 31	$ (570)	$ (2,210)