Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (350,544)	$ (285,620)	$ (268,113)
Other comprehensive loss:
Unrealized gain (loss) on available-for-sale securities	126	(397)	138
Comprehensive loss	(350,418)	(286,017)	(267,975)
Comprehensive loss (income) attributable to noncontrolling interest (SRX Cardio)	321	(470)	(930)
Total comprehensive loss attributable to Portola	$ (350,097)	$ (286,487)	$ (268,905)