Equity-based Awards, Unit Option Awards (Details) (Unit Option Awards [Member], USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended			12 Months Ended
	Mar. 31, 2013 Y		Mar. 31, 2012	Dec. 31, 2012
Summary of awards activity, options [Roll Forward]
Beginning of period (in units)	2,761,140
Exercised (in units)	(646,000)
End of period (in units)	2,115,140			2,761,140
Options outstanding, weighted-average strike price [Roll Forward]
Weighted average strike price, beginning of period (in dollars per unit)	$ 27.41
Weighted average strike price, exercised (in dollars per unit)	$ 30.83
Weighted average strike price, end of period (in dollars per unit)	$ 26.36			$ 27.41
Weighted average remaining contractual term	2 years 1 month			2 years
Aggregate intrinsic value	$ 27.3	[1]		$ 13.0	[1]
Exercisable (in units)	30,000
Exercisable - Weighted average strike price (in dollars per unit)	$ 30.93
Exercisable - Weighted average remaining contractual term (in years)	0.8
Exercisable - Aggregate intrinsic value	0.9	[1]
Total intrinsic value of unit option awards exercised during period	16.4		14.0
Cash received from EPCO in connection with the exercise of unit option awards	9.5		10.2
Unit option award-related cash reimbursements to EPCO	16.4		14.0
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost	0.5
Recognition period for total unrecognized compensation cost	0 years 10 months
Enterprise [Member]
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost	$ 0.4

[1] Aggregate intrinsic value reflects fully vested unit option awards at the date indicated.