Retirement Plans (Details 9) (Pension Benefits [Member])	Dec. 31, 2011	Dec. 31, 2010
Pension plans asset allocations
Pension Plans Asset Allocations	100.00%	100.00%
U.S. Equity [Member]
Pension plans asset allocations
Pension Plans Asset Allocations	14.00%	15.10%
Global ex U.S. Equity [Member]
Pension plans asset allocations
Pension Plans Asset Allocations	10.40%	11.60%
Emerging Markets Equity [Member]
Pension plans asset allocations
Pension Plans Asset Allocations	3.60%	3.50%
Absolute Return Hedge Funds [Member]
Pension plans asset allocations
Pension Plans Asset Allocations	11.70%	11.70%
Equity Hedge Funds [Member]
Pension plans asset allocations
Pension Plans Asset Allocations	10.70%	12.90%
Private Equity [Member]
Pension plans asset allocations
Pension Plans Asset Allocations	4.70%	4.20%
Private Real Assets [Member]
Pension plans asset allocations
Pension Plans Asset Allocations	1.60%	1.00%
Public Real Assets [Member]
Pension plans asset allocations
Pension Plans Asset Allocations	2.00%	2.40%
Fixed Income [Member]
Pension plans asset allocations
Pension Plans Asset Allocations	40.00%	36.70%
Cash Equivalents [Member]
Pension plans asset allocations
Pension Plans Asset Allocations	1.30%	0.90%