Document and Entity Information	Sep. 18, 2019
Cover [Abstract]
Entity Registrant Name	PORTOLA PHARMACEUTICALS INC
Amendment Flag	false
Entity Central Index Key	0001269021
Document Type	8-K
Document Period End Date	Sep. 18, 2019
Entity Incorporation State Country Code	DE
Entity File Number	001-35935
Entity Tax Identification Number	20-0216859
Entity Address, Address Line One	270 E. Grand Avenue
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	(650)
Local Phone Number	246-7300
Written Communications	false
Soliciting Material	false
Pre Commencement Tender Offer	false
Pre Commencement Issuer Tender Offer	false
Security 12b Title	Common Stock
Trading Symbol	PTLA
Security Exchange Name	NASDAQ
Entity Emerging Growth Company	false