Cover Page	3 Months Ended
	Mar. 31, 2020 shares
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	001-35349
Entity Registrant Name	Phillips 66
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	45-3779385
Entity Address, Address Line One	2331 CityWest Blvd
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77042
City Area Code	281
Local Phone Number	293-6600
Title of 12(b) Security	Common Stock, $0.01 Par Value
Trading Symbol	PSX
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity common stock, shares outstanding (in shares)	436,674,707
Entity Central Index Key	0001534701
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Amendment Flag	false