Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Collaboration and license revenue	$ 12,070,000	$ 9,625,000	$ 10,531,000
Operating expenses:
Research and development	200,376,000	123,639,000	79,286,000
Selling, general and administrative	38,869,000	23,552,000	15,423,000
Total operating expenses	239,245,000	147,191,000	94,709,000
Loss from operations	(227,175,000)	(137,566,000)	(84,178,000)
Interest and other income, net	305,000	441,000	826,000
Loss before taxes	(226,870,000)	(137,125,000)	(83,352,000)
Income tax benefit	365,000	0	0
Net loss	(226,505,000)	(137,125,000)	(83,352,000)
Net loss attributable to Portola	$ (226,505,000)	$ (137,125,000)	$ (83,352,000)
Net loss per share attributable to Portola common stockholders:
Basic and diluted	$ (4.36)	$ (3.19)	$ (3.65)
Shares used to compute net loss per share attributable to Portola common stockholders:
Basic and diluted	51,981,463	42,977,463	22,842,443