Equity and Distributions, Summary of Changes in Outstanding Units (Details)	9 Months Ended
	Sep. 30, 2013
Common Units (Unrestricted) [Member]
Summary of changes in outstanding units [Roll Forward]
Number of units outstanding at December 31, 2012 (in units)	894,919,851
Common units issued in connection with underwritten offering (in units)	9,200,000
Common units issued in connection with our at-the-market program (in units)	7,284,807
Common units issued in connection with our DRIP and EUPP (in units)	3,760,154
Common units issued in connection with the vesting of unit options (in units)	200,882
Common units issued in connection with the vesting of restricted common unit awards (in units)	1,846,198
Conversion and reclassification of Class B units to common units (in units)	4,520,431
Restricted common units awards issued (in units)	0
Forfeiture of restricted common unit awards (in units)	0
Acquisition and cancellation of treasury units in connection with the vesting of equity-based awards (in units)	(618,317)
Number of units outstanding at September 30, 2013	921,114,006
Restricted Common Units [Member]
Summary of changes in outstanding units [Roll Forward]
Number of units outstanding at December 31, 2012 (in units)	3,893,486
Common units issued in connection with underwritten offering (in units)	0
Common units issued in connection with our at-the-market program (in units)	0
Common units issued in connection with our DRIP and EUPP (in units)	0
Common units issued in connection with the vesting of unit options (in units)	0
Common units issued in connection with the vesting of restricted common unit awards (in units)	(1,846,198)
Conversion and reclassification of Class B units to common units (in units)	0
Restricted common units awards issued (in units)	1,769,076
Forfeiture of restricted common unit awards (in units)	(159,832)
Acquisition and cancellation of treasury units in connection with the vesting of equity-based awards (in units)	0
Number of units outstanding at September 30, 2013	3,656,532
Common units [Member]
Summary of changes in outstanding units [Roll Forward]
Number of units outstanding at December 31, 2012 (in units)	898,813,337
Common units issued in connection with underwritten offering (in units)	9,200,000
Common units issued in connection with our at-the-market program (in units)	7,284,807
Common units issued in connection with our DRIP and EUPP (in units)	3,760,154
Common units issued in connection with the vesting of unit options (in units)	200,882
Common units issued in connection with the vesting of restricted common unit awards (in units)	0
Conversion and reclassification of Class B units to common units (in units)	4,520,431
Restricted common units awards issued (in units)	1,769,076
Forfeiture of restricted common unit awards (in units)	(159,832)
Acquisition and cancellation of treasury units in connection with the vesting of equity-based awards (in units)	(618,317)
Number of units outstanding at September 30, 2013	924,770,538