Consolidated Statement of Changes in Equity - USD ($) $ in Millions		Total		Sweeny Fractionator Acquisition [Member]	Subsequent Fractionator Acquisition [Member]	Explorer Pipeline Company, DCP Sand Hills Pipeline LLC, DCP Southern Hills Pipeline LLC [Member]	Net Investment [Member]		General Partner [Member]	General Partner [Member] Sweeny Fractionator Acquisition [Member]	General Partner [Member] Subsequent Fractionator Acquisition [Member]	General Partner [Member] Explorer Pipeline Company, DCP Sand Hills Pipeline LLC, DCP Southern Hills Pipeline LLC [Member]	Accumulated Other Comprehensive Loss [Member]	Common Units [Member] Public [Member]	Common Units [Member] Non-public [Member] Phillips 66 [Member]	Common Units [Member] Non-public [Member] Phillips 66 [Member] Sweeny Fractionator Acquisition [Member]	Common Units [Member] Non-public [Member] Phillips 66 [Member] Subsequent Fractionator Acquisition [Member]	Common Units [Member] Non-public [Member] Phillips 66 [Member] Explorer Pipeline Company, DCP Sand Hills Pipeline LLC, DCP Southern Hills Pipeline LLC [Member]	Subordinated Units [Member] Non-public [Member] Phillips 66 [Member]
Beginning Balance at Dec. 31, 2014		$ 163.9					$ 91.7	[1]	$ (517.0)					$ 415.3	$ 57.1				$ 116.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Less: Net income (loss) attributable to Predecessors	[1]	(1.0)					(1.0)
Net contributions from Phillips 66—Predecessors		36.1					36.1	[1]
Issuance of common units		383.9												383.9
Conversion of subordinated units															105.8				(105.8)
Deemed net distributions to General Partner associated with acquisitions		(145.0)							(145.0)
Net income attributable to the Partnership		129.7	[1]						26.9					30.3	58.5				14.0
Other comprehensive loss		(1.5)											$ (1.5)
Quarterly cash distributions to unitholders and General Partner		(107.3)							(18.8)					(25.0)	(38.5)				$ (25.0)
Other contributions from Phillips 66		4.1							4.1
Ending Balance at Sep. 30, 2015	[1]	$ 462.9					126.8		$ (649.8)				(1.5)	$ 804.5	$ 182.9
Units at Dec. 31, 2014		76,575,878							1,531,518					18,888,750	20,938,498				35,217,112
Units Outstanding [Roll Forward]
Units issued in public equity offerings		5,250,000												5,250,000
Units issued associated with acquisition						1,726,914						139,538						1,587,376
Subordinated unit conversion															35,217,112				(35,217,112)
Units at Sep. 30, 2015		83,552,792							1,671,056					24,138,750	57,742,986
Beginning Balance at Dec. 31, 2015		$ 504.0					113.9	[1]	$ (650.3)				(1.5)	$ 808.9	$ 233.0				$ 0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Less: Net income (loss) attributable to Predecessors		18.1					18.1	[1]
Net contributions from Phillips 66—Predecessors		134.5					134.5	[1]
Issuance of common units		971.6												971.6
Allocation of net investment to unitholders							$ (266.5)	[1]	34.0						232.5
Net income attributable to the Partnership		202.9							62.9					51.2	88.8
Other comprehensive loss		0.3											0.3
Quarterly cash distributions to unitholders and General Partner		(176.8)							(50.0)					(41.4)	(85.4)
Other contributions from Phillips 66		3.8							3.8
Ending Balance at Sep. 30, 2016		$ 1,658.4							$ (599.6)				$ (1.2)	$ 1,790.3	$ 468.9
Units at Dec. 31, 2015		84,171,217							1,683,425					24,138,750	58,349,042
Units Outstanding [Roll Forward]
Units issued in public equity offerings		18,996,152												18,996,152
Units issued associated with acquisition	[2]			421,248	1,687,675					8,425	286,753					412,823	1,400,922
Units at Sep. 30, 2016		105,276,292							1,978,603					43,134,902	60,162,787

[1] Prior-period financial information has been retrospectively adjusted for acquisitions of businesses under common control.

[2] See Note 4—Fractionator Acquisitions, in the Notes to Consolidated Financial Statements.