Net Income Per Limited Partner Unit - Schedule of Basic and Diluted Net Income Per Unit (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Distribution Made To Limited Partner [Line Items]
Distributions declared		$ 162
Distributions in excess of net income		(24)
Net income attributable to the Partnership	$ 163	138
Net income attributable to the Partnership’s common unitholders (basic)	151
Dilutive effect of preferred units	12
General Partner SPLC
Distribution Made To Limited Partner [Line Items]
Distributions declared		55
Distributions in excess of net income		0
Net income attributable to the Partnership		55
Limited Partners’ Common Units
Distribution Made To Limited Partner [Line Items]
Distributions declared		107
Distributions in excess of net income		(24)
Net income attributable to the Partnership		$ 83
Net income attributable to the Partnership’s common unitholders (diluted)	$ 163
Weighted average units outstanding (in millions)
Weighted average units outstanding - Basic (in shares)	393.3
Dilutive effect of preferred units (in shares)	50.8
Weighted average units outstanding - Diluted (in shares)	444.1
Weighted average units outstanding, basic and diluted (in shares)		233.3
Net income per Limited Partner Unit (in dollars)
Net income per Limited Partner Unit - basic (in dollars per share)	$ 0.38	$ 0.36
Net income per Limited Partner Unit - diluted (in dollars per share)	$ 0.37	0.36
Net income per Limited Partner unit, basic and diluted (in dollars per share)		$ 0.36