Employee Benefits Plans (Details 13) (Other Postretirement Benefits [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Other Postretirement Benefits [Member]
Amounts recognized in the Consolidated Balance Sheets
Current liability	$ (2,838)	$ (3,382)
Noncurrent liability	(40,154)	(43,787)
Net amount recognized	(42,992)	(47,169)
Amounts recognized in accumulated other comprehensive loss (pre-tax)
Prior service credit	(1,538)	(1,769)
Net actuarial loss	867	6,901
Net amount recognized	$ (671)	$ 5,132