Benefit Obligations (Details 13)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Benefits [Member]
Actuarial assumptions
Discount rate to determine net periodic cost	5.25%	5.75%	6.50%
Discount rate to determine the benefit obligation as of December 31	4.30%	5.25%	5.75%
Rate of compensation increase to determine net periodic cost	0.00%	0.00%	4.00%
Rate of compensation increase to determine the benefit obligation as of December 31	0.00%	0.00%	0.00%
Expected average rate of return on plan assets	7.75%	8.00%
Post-retirement Benefits [Member]
Actuarial assumptions
Discount rate to determine net periodic cost	5.70%	6.00%	6.50%
Discount rate to determine the benefit obligation as of December 31	4.50%	5.70%	6.00%
Rate of compensation increase to determine net periodic cost	3.50%	4.00%	4.00%
Rate of compensation increase to determine the benefit obligation as of December 31	3.50%	3.50%	4.00%
Expected average rate of return on plan assets	6.20%	7.00%	7.50%
Rate for management plan [Member] | Pension Benefits [Member]
Actuarial assumptions
Expected average rate of return on plan assets			8.25%
Rate for represented plan [Member]
Actuarial assumptions
Expected average rate of return on plan assets			8.00%