Retirement and Employee Benefit Plans (Weighted Average Assumptions Used in the Measurement of Net Periodic Benefit Cost) (Details)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Benefits [Member]
Discount rate	5.50%	5.75%	6.00%
Expected return on plan assets	7.50%	7.50%	7.50%
Rate of compensation increase	4.50%	4.50%	4.50%
Other Postretirement Benefits [Member]
Discount rate	5.50%	5.75%	6.00%
Expected return on plan assets	0.00%	0.00%	0.00%
Rate of compensation increase	0.00%	0.00%	0.00%