Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (68,771)	$ (78,096)
Other comprehensive income:
Unrealized gain on available-for-sale securities	561	203
Foreign currency translation adjustment	232	0
Comprehensive loss	(67,978)	(77,893)
Comprehensive income attributable to noncontrolling interest	0	(60)
Total comprehensive loss attributable to Portola	$ (67,978)	$ (77,953)