Cover Page - shares	9 Months Ended
	Oct. 31, 2020	Dec. 04, 2020
Entity Addresses [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Oct. 31, 2020
Document Transition Report	false
Entity File Number	001-38977
Entity Registrant Name	PHREESIA, INC.
Amendment Flag	false
Entity Central Index Key	0001412408
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--01-31
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-2275479
Entity Address, Address Line One	434 Fayetteville St
Entity Address, Address Line Two	Suite 1400
Entity Address, City or Town	Raleigh
Entity Address, State or Province	NC
Entity Address, Postal Zip Code	27601
City Area Code	888
Local Phone Number	654-7473
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	PHR
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		44,162,852
Former Address
Entity Addresses [Line Items]
Entity Address, Address Line One	432 Park Ave. S.
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10016