Equity and Distributions (Details) (USD $) In Millions, except Share data, unless otherwise specified			3 Months Ended
	Mar. 31, 2013 Class B units [Member]	Dec. 31, 2012 Class B units [Member]	Mar. 31, 2013 Treasury Units [Member]
Mergers [Line Items]
Units outstanding (in units)	4,520,431	4,520,431
Treasury Units [Abstract]
Conversion of restricted units and similar awards to common units (in units)			939,226
Acquisition of treasury units in connection with vesting of equity-based awards (in units)			315,783
Total cost of treasury units			$ 17.7