Long-Term Debt (Parenthetical) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014 ENLC Credit Facility [Member]	Sep. 30, 2014 2.7% Senior Notes due 2019 [Member]	Sep. 30, 2014 4.4% Senior Notes due 2024 [Member]	Sep. 30, 2014 5.6% Senior Notes due 2044 [Member]	Sep. 30, 2014 7.125% Senior Notes due 2022 [Member]	Mar. 07, 2014 7.125% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Interest Rate During Period	1.90%	1.90%
Debt Instrument, Interest Rate, Stated Percentage			2.70%	4.40%	5.60%	7.125%	7.125%
Debt Instrument, Unamortized Discount (Premium), Net			$ 2.7	$ 3.5	$ 3.3	$ (22.6)	$ (29.5)