Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (82,941)	$ (91,036)	$ (194,119)	$ (213,349)
Other comprehensive income (loss):
Unrealized gain (loss) on available-for-sale securities, net of tax	33	(49)	(25)	194
Comprehensive loss	(82,908)	(91,085)	(194,144)	(213,155)
Comprehensive loss (income) attributable to noncontrolling interest (SRX Cardio)	5	(1,853)	(190)	(1,853)
Total comprehensive loss attributable to Portola	$ (82,903)	$ (92,938)	$ (194,334)	$ (215,008)