Net Income Per Limited Partner Unit - Schedule of Allocation of Net Income to Arrive at Net Income Per Limited Partner Unit (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Limited Partners Capital Account [Line Items]
Net income	$ 144	$ 146	$ 119	$ 137	$ 147	$ 155	$ 115	$ 65	$ 546	$ 482	$ 392
Net income attributable to the Parent									0	0	77
Net income attributable to noncontrolling interests									18	18	20
Net income attributable to the Partnership	$ 140	$ 141	$ 115	$ 132	$ 140	$ 149	$ 111	$ 64	528	464	295
Partner distribution declared									552	469	292
Income (less than)/in excess of distributions									(24)	(5)	3
General Partner
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership									147	134	64
Partner distribution declared									148	135	64
Income (less than)/in excess of distributions									(1)	(1)	0
Common
Limited Partners Capital Account [Line Items]
Net income attributable to the Partnership									381	330	231
Partner distribution declared									404	334	228
Income (less than)/in excess of distributions									$ (23)	$ (4)	$ 3