Receivables (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Receivables [Abstract]
Trade receivables	$ 1,736.2	$ 1,523.5
Insurance company receivable related to the indemnity settlement with BPExploration and Production Inc.	0	167.5
Other receivables	172.2	76.2
Allowance for doubtful accounts	(9.0)	(9.9)
Total receivables	$ 1,899.4	$ 1,757.3