Condensed Consolidated Statements of Operations (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Cost of Purchased Oil and Gas	$ 597.2	$ 435.5	$ 1,798.0	$ 1,279.6
Operating Costs and Expenses	76.7	35.8	195.5	116.0
General and Administrative Expense	24.5	10.8	66.9	32.3
Affiliated Entity [Member]
Cost of Purchased Oil and Gas	24.1	397.8	349.9	1,170.4
Operating Costs and Expenses	0	8.9	5.9	26.9
General and Administrative Expense	$ 1.0	$ 10.8	$ 10.6	$ 32.3