Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (64,974)	$ (46,913)
Other comprehensive income:
Unrealized gain on available-for-sale securities, net of tax	216	169
Comprehensive loss	(64,758)	(46,744)
Total comprehensive loss attributable to Portola	$ (64,758)	$ (46,744)