Units Outstanding (Details) - shares	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Units Outstanding
Outstanding as of December 31, 2018 (in units)	268,850,276
Options exercised (in units)	406,235	500,000
Units issued (in units)	2,068,514
Units retired (in units)	(2,509,460)
Balance as of June 30, 2019 (in units)	268,815,565
Limited Partners' Capital Account [Line Items]
Units purchased and retired (in units)	2,509,460
AB Units
Units Outstanding
Units retired (in units)	(882)
Limited Partners' Capital Account [Line Items]
Units purchased and retired (in units)	882