Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Aug. 01, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Trading Symbol	PTLA
Entity Registrant Name	PORTOLA PHARMACEUTICALS INC
Entity Central Index Key	0001269021
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		68,323,733
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity File Number	001-35935
Entity Tax Identification Number	200216859
Entity Address, Address Line One	270 E. Grand Avenue
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	California
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	246-7000