Cash Flow Information (Summary of Cash Flow Information) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Capital Expenditures And Investments [Abstract]
Capital expenditures attributable to Predecessors	[1]	$ 19.0	$ 180.1
Capital expenditures attributable to noncontrolling interest		5.2
Capital expenditures and investments attributable to the Partnership		32.8	32.9
Cash capital expenditures and investments		77.0	161.7	[1]
Change In capital expenditure accruals		(20.0)
Change in capital expenditure accruals	[1]		51.3
Total capital expenditures and investments	[1]	57.0	213.0
Noncash Investing and Financing Items [Abstract]
Contributions of net assets into joint ventures			$ 45.5
Phillips 66 [Member] | Sweeny Fractionator Acquisition [Member] | Phillips 66 [Member]
Noncash Investing and Financing Items [Abstract]
Transfer of net liabilities to Phillips 66—Sweeny Fractionator Acquisition		$ 33.6

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