Consolidated Statement of Income - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015		Sep. 30, 2016	Sep. 30, 2015
Revenues and Other Income
Operating revenues—related parties		$ 108.4	$ 71.1	[1]	$ 315.7	$ 204.0	[1]
Operating revenues—third parties		1.8	0.7	[1]	5.9	2.7	[1]
Equity in earnings of affiliates		33.8	25.2	[1]	88.5	51.9	[1]
Other income		0.3	0.1	[1]	0.8	0.2	[1]
Total revenues and other income		144.3	97.1	[1]	410.9	258.8	[1]
Costs and Expenses
Operating and maintenance expenses		25.5	20.3	[1]	76.4	56.3	[1]
Depreciation		15.1	6.1	[1]	43.5	16.8	[1]
General and administrative expenses		9.2	7.4	[1]	26.0	23.2	[1]
Taxes other than income taxes		1.2	3.1	[1]	12.3	8.9	[1]
Interest and debt expense		9.9	9.2	[1]	30.8	24.6	[1]
Other expenses		0.1			0.1	0.1	[1]
Total costs and expenses		61.0	46.1	[1]	189.1	129.9	[1]
Income before income taxes		83.3	51.0	[1]	221.8	128.9	[1]
Provision for income taxes		0.2	0.1		0.8	0.2
Net Income		83.1	50.9	[1]	221.0	128.7	[1]
Less: Net income (loss) attributable to Predecessors			(1.4)	[1]	18.1	(1.0)	[1]
Net income attributable to the Partnership		83.1	52.3	[1]	202.9	129.7	[1]
Less: General partner’s interest in net income attributable to the Partnership		26.0	11.5	[1]	62.9	26.9	[1]
Limited partners’ interest in net income attributable to the Partnership		$ 57.1	$ 40.8	[1]	$ 140.0	$ 102.8	[1]
Net Income Attributable to the Partnership Per Limited Partner Unit—Basic and Diluted (dollars)
Cash Distributions Paid Per Limited Partner Unit (dollars)		$ 0.505	$ 0.4	[1]	$ 1,444,000.000	$ 1.11	[1]
Common Units [Member]
Net Income Attributable to the Partnership Per Limited Partner Unit—Basic and Diluted (dollars)
Basic, per unit (dollars)		0.57	0.50	[1]	1.53	1.40	[1]
Diluted, per unit (dollars)		$ 0.57	$ 0.50	[1]	$ 1.53	$ 1.40	[1]
Average Limited Partner Units Outstanding—Basic and Diluted (thousands)
Basic, units		100,555,277	81,881,736		91,414,459	63,485,577
Diluted, units		100,555,277	81,881,736		91,414,459	63,485,577
Common Units [Member] | Public [Member]
Costs and Expenses
Net income attributable to the Partnership					$ 51.2	$ 30.3
Average Limited Partner Units Outstanding—Basic and Diluted (thousands)
Basic, units		40,392,000	24,139,000	[1]	32,007,000	23,120,000	[1]
Diluted, units		40,392,000	24,139,000		32,007,000	23,120,000
Common Units [Member] | Non-public [Member] | Phillips 66 [Member]
Costs and Expenses
Net income attributable to the Partnership					$ 88.8	$ 58.5
Average Limited Partner Units Outstanding—Basic and Diluted (thousands)
Basic, units		60,163,000	57,743,000	[1]	59,408,000	40,366,000	[1]
Diluted, units		60,163,000	57,743,000		59,408,000	40,366,000
Subordinated Units [Member]
Net Income Attributable to the Partnership Per Limited Partner Unit—Basic and Diluted (dollars)
Basic, per unit (dollars)			$ 0.00		$ 0.00	$ 0.82
Diluted, per unit (dollars)			$ 0.00		$ 0.00	$ 0.82
Average Limited Partner Units Outstanding—Basic and Diluted (thousands)
Basic, units			0		0	17,028,054
Diluted, units			0		0	17,028,054
Subordinated Units [Member] | Non-public [Member] | Phillips 66 [Member]
Costs and Expenses
Net income attributable to the Partnership						$ 14.0
Net Income Attributable to the Partnership Per Limited Partner Unit—Basic and Diluted (dollars)
Basic, per unit (dollars)	[1]		$ 0.00			$ 0.82
Diluted, per unit (dollars)			$ 0.00	[1]	$ 0.00	$ 0.82	[1]
Average Limited Partner Units Outstanding—Basic and Diluted (thousands)
Basic, units	[1]		0			17,028,000
Diluted, units		0	0			17,028,000

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