Employee Benefit Plans (Details 5) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Benefits [Member]
Estimated amounts that will be amortized from accumulated other comprehensive loss
Actuarial loss	$ 70,884
Prior service credit	(6,959)
Total	63,925
Assumptions used in measuring net periodic benefit costs
Weighted average discount rate	5.74%	6.54%	6.97%
Rate of increase in future compensation levels	3.39%	3.75%	3.75%
Expected long-term rate of return on plan assets	7.87%	8.00%	8.00%
Other Postretirement Benefits [Member]
Estimated amounts that will be amortized from accumulated other comprehensive loss
Actuarial loss	1,266
Prior service credit	(930)
Total	$ 336
Assumptions used in measuring net periodic benefit costs
Weighted average discount rate	4.25%	5.20%	5.79%