Debt (Details 4) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Feb. 29, 2008
Revolving Loans
Revolving loans
Weighted Average Interest Rate (as a percent)	1.40%
Total Amount Committed by Lenders	$ 428.7
Outstanding Borrowings	216.5
Outstanding Letters of Credit	115.4
Total Amount Available	96.8
U.S. Dollar revolving loans under the Amended Credit Agreement
Revolving loans
Weighted Average Interest Rate (as a percent)	1.40%
Total Amount Committed by Lenders	250.0	230.0
Outstanding Borrowings	216.5
Outstanding Letters of Credit	0.2
Total Amount Available	33.3
Other revolving loans
Revolving loans
Total Amount Committed by Lenders	178.7
Outstanding Letters of Credit	115.2
Total Amount Available	$ 63.5