Units Outstanding (Details) - shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Units Outstanding
Outstanding as of December 31, 2016 (in units)	268,893,534
Options exercised (in units)	1,039,632	100,000
Units issued (in units)	1,944,310
Units retired (in units)	(6,053,419)
Balance as of September 30, 2017 (in units)	265,824,057
Limited Partners' Capital Account [Line Items]
Units purchased and retired (in units)	6,053,419
AB Units
Units Outstanding
Units retired (in units)	(43,600)
Limited Partners' Capital Account [Line Items]
Units purchased and retired (in units)	43,600