Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016		Mar. 31, 2015
Operating activities
Net loss	$ (64,974)		$ (46,913)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation and amortization	457		389
Amortization of premium on investment securities	474		932
Stock-based compensation expense	7,069		5,172
Changes in operating assets and liabilities:
Receivables from collaborators			45
Prepaid research and development	6,122		(7,076)
Prepaid expenses and other current assets	(236)		798
Prepaid and other long-term assets	816		934
Accounts payable	3,344		(8,827)
Accrued compensation and employee benefits	(2,750)		(1,754)
Accrued research and development	(6,621)
Accrued and other liabilities	137		10,420
Deferred revenue	17,992		(2,358)
Other long-term liabilities	(166)		1,093
Net cash used in operating activities	(38,336)		(47,145)
Investing activities
Purchases of property and equipment	(1,335)		(1,063)
Decrease in restricted cash (Development Partner)	79
Purchases of investments	(52,544)		(90,940)
Proceeds from maturities of investments	115,684		101,439
Net cash provided by investing activities	61,884		9,436
Financing activities
Proceeds from public offering of common stock, net of underwriters discount			108,772
Payment of public offering cost	(242)
Proceeds from issuance of common stock pursuant to equity award plans	910		4,269
Net cash provided by financing activities	668		113,041
Net increase in cash and cash equivalents	24,216		75,332
Cash and cash equivalents at beginning of period	186,488	[1]	57,514
Cash and cash equivalents at end of period	$ 210,704	[1]	$ 132,846

[1] Amounts include the assets and liabilities of our Development Partner a consolidated variable interest entity (“VIE”). Portola's interests and obligations with respect to the VIE's assets and liabilities are limited to those accorded to Portola in its agreement with the VIE. See Note 7, “Asset Acquisition and License Agreements,” to these condensed consolidated financial statements.