Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Jan. 31, 2011
Purchases from subsidiaries	$ 12.2	$ 0.3
Consultant fee			0.3
Osage Pipeline Co. [Member]
Interest in equity method investment	50.00%
Operating fees received for crude oil pipeline	0.2	0.2
Texas Frontera LLC [Member]
Interest in equity method investment	50.00%
Construction funding request	2.5
Construction funding request, paid in cash	1.5
Construction funding request, applied against capital spending	1.0
Double Eagle Pipeline LLC [Member]
Interest in equity method investment	50.00%
Construction funding request	$ 2.0