Partners' Capital and Distributions - Preferred Unit Distributions (Details) - USD ($) $ in Millions		12 Months Ended
	Feb. 12, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Partners Capital and Distribution [Line Items]
Number of days after end of quarter within which distributions must be paid to unitholders		45 days
Cash Distribution | Series B Preferred Units
Partners Capital and Distribution [Line Items]
Preferred unit dividends		$ 49	$ 49	$ 49
Cash Distribution | Series A Preferred Units
Partners Capital and Distribution [Line Items]
Preferred unit dividends		$ 149	$ 149	$ 112
Unit Distribution | Series A Preferred Units
Partners Capital and Distribution [Line Items]
Unit distributions (in units)		0	0	1,393,926
Distributions paid to unitholders				$ 37
Other current liabilities | Series B Preferred Units
Partners Capital and Distribution [Line Items]
Dividends payable		$ 6
Other current liabilities | Subsequent Event | Cash Distribution | Series A Preferred Units
Partners Capital and Distribution [Line Items]
Preferred unit dividends	$ 37