UNAUDITED CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares	Mar. 31, 2021	Dec. 31, 2020
Common unitholders' capital account, units outstanding (in shares)	393,289,537	393,289,537
Shell Pipeline Company L P
Preferred units, issued (in shares)	50,782,904	50,782,904
Preferred units, outstanding (in shares)	50,782,904	50,782,904
Common Units
Common unitholders' capital account, units issued (in shares)	123,832,233	123,832,233
Common unitholders' capital account, units outstanding (in shares)	123,832,233	123,832,233
Common Units | Shell Pipeline Company L P
Common unitholders' capital account, units issued (in shares)	269,457,304	269,457,304
Common unitholders' capital account, units outstanding (in shares)	269,457,304	269,457,304