Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (105,971)	$ (69,414)	$ (190,481)	$ (111,178)
Other comprehensive loss:
Unrealized gain (loss) on available-for-sale securities, net of tax	127	21	(265)	(58)
Comprehensive loss	(105,844)	(69,393)	(190,746)	(111,236)
Comprehensive (income) loss attributable to noncontrolling interest (SRX Cardio)	(223)	(240)	109	(195)
Total comprehensive loss attributable to Portola	$ (106,067)	$ (69,633)	$ (190,637)	$ (111,431)