UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares	Mar. 31, 2019	Dec. 31, 2018
Common unitholders' capital account, units outstanding (in shares)	223,811,781
Shell Pipeline Company L P
General partners' capital account, units issued (in shares)	4,567,588	4,567,588
General partners' capital account, units outstanding (in shares)	4,567,588	4,567,588
Common Units | General Public
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)	99,979,548	99,979,548
Common unitholders' capital account, units outstanding (in shares)	99,979,548	99,979,548