Units Outstanding (Details) - shares	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Units Outstanding
Outstanding as of December 31, 2016 (in units)	268,893,534
Options exercised (in units)	545,458	100,000
Units issued (in units)	1,876,205
Units retired (in units)	(5,601,111)
Balance as of June 30, 2017 (in units)	265,714,086
Limited Partners' Capital Account [Line Items]
Units purchased and retired (in units)	5,601,111
AB Units
Units Outstanding
Units retired (in units)	(30,400)
Limited Partners' Capital Account [Line Items]
Units purchased and retired (in units)	30,400