Equity-based Awards (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Equity-based compensation expense [Abstract]
Total compensation expense	$ 17.5	$ 17.2
Equity-classified awards [Member] | Restricted Common Unit Awards [Member]
Equity-based compensation expense [Abstract]
Total compensation expense	11.6	16.6
Equity-classified awards [Member] | Unit Option Awards [Member]
Equity-based compensation expense [Abstract]
Total compensation expense	0	0.4
Equity-classified awards [Member] | Phantom Unit Awards [Member]
Equity-based compensation expense [Abstract]
Total compensation expense	5.8	0
Liability-classified awards [Member]
Equity-based compensation expense [Abstract]
Total compensation expense	$ 0.1	$ 0.2
Long-Term Incentive Plan (2008) [Member]
Equity-based compensation expense [Abstract]
Incremental number of units to be authorized annually (in units)	2,500,000
Maximum number of additional units to be authorized for issuance (in units)	35,000,000
Maximum number of common units that may be issued as awards (in units)	12,500,000
Remaining number of common units available to be issued as awards (in units)	6,303,256
Long Term Incentive Plan (1998) [Member]
Equity-based compensation expense [Abstract]
Maximum number of common units that may be issued as awards (in units)	7,000,000
Remaining number of common units available to be issued as awards (in units)	1,321,380