CONSOLIDATED STATEMENTS OF CHANGES IN (DEFICIT) EQUITY - USD ($) $ in Millions	Total	Common unitholders - public	Common unitholders - public Shell Pipeline Company L P	Subordinated Units Shell Pipeline Company L P	General Partner Shell Pipeline Company L P	Noncontrolling Interest	Net Parent Investment
Beginning balance at Dec. 31, 2015	$ 632.5	$ 1,637.5	$ (130.4)	$ (409.8)	$ (998.6)	$ 108.4	$ 425.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	377.5	107.2	27.2	85.5	25.0	30.3	102.3
Net proceeds from public offerings	818.1	818.1
Contributions from general partner	16.9				16.9
Other contributions from Parent	9.7				3.0		6.7
Distributions to noncontrolling interest	(30.2)					(30.2)
Distributions to unitholders and general partner	(179.9)	(77.1)	(20.9)	(65.3)	(16.6)
Acquisition of noncontrolling interest	(87.0)					(87.0)
Capital distributions to general partner	(903.4)				(903.4)
Net distributions to Parent	(120.0)						(120.0)
Ending balance at Dec. 31, 2016	534.2	2,485.7	(124.1)	(389.6)	(1,873.7)	21.5	414.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	391.8	118.4	112.3	0.0	64.6	19.2	77.3
Net proceeds from public offerings	277.9	277.9			0.0
Contributions from general partner	5.8				5.8
Other contributions from Parent	17.1				17.1		0.0
Distributions to noncontrolling interest	(18.9)					(18.9)
Distributions to unitholders and general partner	(267.8)	(108.5)	(87.1)	(18.7)	(53.5)
Acquisitions from Parent	(1,455.0)				(1,034.5)		(420.5)
Net distributions to Parent	(65.6)						(65.6)
Proceeds from April 2017 divestiture	20.2				18.7	1.5
Expiration of subordinated period	0.0		(408.3)	408.3
Net assets not contributed to the partnership	(5.6)						(5.6)
Ending balance at Dec. 31, 2017	(565.9)	2,773.5	(507.2)	0.0	(2,855.5)	23.3	0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	482.4	182.4	147.3		134.4	18.3
Net proceeds from public offerings	973.3	673.3	300.0
Contributions from general partner	20.0				20.0
Other contributions from Parent	13.4				13.5	(0.1)
Distributions to noncontrolling interest	(16.4)					(16.4)
Distributions to unitholders and general partner	(423.1)	(168.5)	(139.1)		(115.5)
May 2018 Acquisitions	(738.4)				(738.4)
Ending balance at Dec. 31, 2018	$ (257.0)	$ 3,459.3	$ (198.0)	$ 0.0	$ (3,543.7)	$ 25.4	$ 0.0