Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (292,876)	$ (350,544)	$ (285,620)
Other comprehensive income (loss):
Unrealized gain (loss) on available-for-sale securities	318	126	(397)
Comprehensive loss	(292,558)	(350,418)	(286,017)
Comprehensive loss (income) attributable to noncontrolling interest	2,213	321	(470)
Total comprehensive loss attributable to Portola	$ (290,345)	$ (350,097)	$ (286,487)