Retirement Plans (Details)	Dec. 31, 2011	Dec. 31, 2010
Pension Benefits [Member]
Weighted-average assumptions used to determine benefit obligations:
Rate of compensation increase	4.80%	4.80%
Maximum [Member] | Pension Benefits [Member]
Weighted-average assumptions used to determine benefit obligations:
Discount rate	4.90%	5.80%
Maximum [Member] | Other Postretirement Benefits [Member]
Weighted-average assumptions used to determine benefit obligations:
Discount rate	4.80%	5.50%
Minimum [Member] | Pension Benefits [Member]
Weighted-average assumptions used to determine benefit obligations:
Discount rate	4.70%	5.40%
Minimum [Member] | Other Postretirement Benefits [Member]
Weighted-average assumptions used to determine benefit obligations:
Discount rate	4.60%	5.30%