Employee Benefit Plans Net Periodic Cost (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the period	$ 1,422	$ 1,360	$ 1,319
Interest cost on projected benefit obligation	7,481	8,131	9,385
Expected return on assets	(8,834)	(8,271)	(7,817)
Prior service cost	0	0	801
Time contractual termination benefits	0	0	(1,808)
Amortization of net loss (gain)	2,807	3,376	2,136
Net expense	2,876	4,596	4,016
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the period	13	13	15
Interest cost on projected benefit obligation	500	521	567
Expected return on assets	0	0	0
Prior service cost	0	0	0
Time contractual termination benefits	0	0	0
Amortization of net loss (gain)	(88)	(129)	(163)
Net expense	$ 425	$ 405	$ 419