Consolidated Balance Sheet (Parenthetical) - shares	Sep. 30, 2020	Dec. 31, 2019
Public
Preferred units, issued (in shares)	13,819,791	13,819,791
Preferred units, outstanding (in shares)	13,819,791	13,819,791
Common Units | Public
Units issued (in shares)	58,580,009	58,539,439
Units outstanding (in shares)	58,580,009	58,539,439
Common Units | Non-public | Phillips 66
Units issued (in shares)	169,760,137	169,760,137
Units outstanding (in shares)	169,760,137	169,760,137