Note 1 - Organization and Basis of Presentation Principles of Consolidated and Basis of Presentation (Details) - USD ($)		3 Months Ended															12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Finite-Lived Intangible Asset, Useful Life																	31 years
Money Market Funds, at Carrying Value		$ 0															$ 0
Interest Costs Capitalized																	13,000,000		$ 8,000,000		$ 6,000,000
Asset Retirement Obligation		10,000,000							$ 11,000,000								10,000,000		11,000,000
Long-term Debt, Gross		5,000,000,000							4,200,000,000								5,000,000,000		4,200,000,000
Debt Instrument, Fair Value Disclosure		$ 4,900,000,000							4,300,000,000								4,900,000,000		4,300,000,000
Reimbursements from Andeavor																	15,000,000		16,000,000		17,000,000
Proceeds From Contributions From Sponsor	[1]																51,000,000		34,000,000		29,000,000
Unit-based compensation expense	[1]																$ 9,000,000		9,000,000		6,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		943,466															943,466
Depreciation																	$ 310,000,000		262,000,000		202,000,000
Revenues		$ 623,000,000	$ 642,000,000	[2]	$ 569,000,000	[2]	$ 546,000,000	[2]	1,114,000,000	[2]	$ 1,094,000,000	[2]	$ 614,000,000	[2]	$ 427,000,000	[2]	2,380,000,000	[3]	3,249,000,000	[3]	1,669,000,000	[3]
Other Income, net	[3]																6,000,000		11,000,000		11,000,000
Limited partners’ interest in net earnings		$ 161,000,000	$ 160,000,000		$ 138,000,000		$ 125,000,000		$ 47,000,000	[4]	$ 97,000,000	[4]	70,000,000	[4]	$ 55,000,000	[4]	584,000,000		267,000,000		187,000,000
Goodwill, Impairment Loss																	0		0		0
Equity Method Investment, Other than Temporary Impairment																	$ 0		0		$ 0
Maximum
Maturity Period Of Short-Term Investments																	3 months
Crude Oil
Products Retained For Volume Losses, Percent																	0.20%
Pipeline Loss Allowance		0.20%															0.20%
Pipeline Loss Allowance, Price Differential		$ 8.00															$ 8.00
Petroleum Products
Products Retained For Volume Losses, Percent																	0.25%
Petroleum Products | Northwest Products System
Products Retained For Volume Losses, Percent																	0.25%
Distillates | Northwest Products System
Products Retained For Volume Losses, Percent																	0.125%
Accounting Standards Update 2016-18 [Member]
Restricted Cash													$ 14,000,000
Accounting Standards Update 2017-07 [Member]
Interest and Debt Expense																			7,000,000
Other Income, net																			7,000,000
Limited partners’ interest in net earnings																			$ 0
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Retained Earnings (Accumulated Deficit)		17,000,000															$ 17,000,000
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2016-02 [Member] | Maximum
Operating Lease, Right-of-Use Asset		145,000,000															145,000,000
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2016-02 [Member] | Minimum
Operating Lease, Right-of-Use Asset		$ 115,000,000															115,000,000
Wholesale [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenues																	2,600,000,000
Cost of Goods and Services Sold																	2,600,000,000
Gathering and Processing [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenues																	$ 6,000,000
PNAC [Member]
Equity Method Investment, Ownership Percentage		50.00%															50.00%

[1] All periods include the historical results of the Predecessors. See Notes 1 and 2 for further discussion.

[2] Adjusted to include the historical results of the Predecessors. See Notes 1 and 2 for further discussion.

[3] All periods include the historical results of the Predecessors. See Notes 1 and 2 for further discussion.

[4] The sum of four quarters may not equal annual results due to rounding or the quarterly number of units outstanding.