Condensed Consolidated Statements of Operations Condensed Consolidated Statements of Operations (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Cost of Purchased Oil and Gas	$ 661.9	$ 448.7	$ 1,200.8	$ 844.1
Operating Costs and Expenses	72.6	39.2	118.7	80.2
General and Administrative Expense	26.6	11.3	42.5	21.5
Affiliated Entity [Member]
Cost of Purchased Oil and Gas	0	410.4	325.8	772.6
Operating Costs and Expenses	0	9.1	5.9	18.0
General and Administrative Expense	$ 1.1	$ 11.3	$ 9.6	$ 21.5