Units Outstanding (Details) - shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Units Outstanding
Outstanding as of December 31, 2018 (in units)	268,850,276
Options exercised (in units)	443,800	600,000
Units issued (in units)	2,073,854
Units retired (in units)	(3,184,973)
Balance as of September 30, 2019 (in units)	268,182,957
Limited Partners' Capital Account [Line Items]
Units purchased and retired (in units)	3,184,973
AB Units
Units Outstanding
Units retired (in units)	(982)
Limited Partners' Capital Account [Line Items]
Units purchased and retired (in units)	982