Related Party Transactions (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Proceeds from Equity Method Investment, Dividends or Distributions	$ 25.1
EFS Midstream [Member]
Cost reimbursement fixed	3.0	2.3	2.2
Cost reimbursement variable	16.4	11.8	8.4
Payments to Acquire Property, Plant, and Equipment	2.8
Right Of Way [Member] | EFS Midstream [Member]
Related party transaction expenses paid		1.9
Gathering And Treating Fees [Member] | EFS Midstream [Member]
Related party transaction expenses paid	$ 81.3	$ 58.5	$ 21.3