Equity-based Awards (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Equity-based compensation expense [Abstract]
Total compensation expense	$ 72.8		$ 60.0		$ 50.9
Restricted Common Unit Awards [Member]
Equity-based compensation expense [Abstract]
Total compensation expense	71.5		57.0		47.5
Unit Option Awards [Member]
Equity-based compensation expense [Abstract]
Total compensation expense	0.8		1.3		3.1
Other [Member]
Equity-based compensation expense [Abstract]
Total compensation expense	$ 0.5	[1]	$ 1.7	[1]	$ 0.3	[1]
Long-Term Incentive Plan (1998) [Member]
Equity-based compensation expense [Abstract]
Maximum number of additional units to be authorized for issuance (in units)	1,155,630
Maximum number of common units that may be issued as awards (in units)	7,000,000
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)	10,000,000
Remaining number of common units available to be issued as awards (in units)	4,348,820

[1] Primarily represents expense associated with unit appreciation rights ("UARs") and similar awards.