Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Revenue:
Research revenue		$ 456fold_ResearchRevenue
Total revenue		456us-gaap_SalesRevenueNet
Operating Expenses:
Research and development	16,113	9,992
General and administrative	6,427us-gaap_GeneralAndAdministrativeExpense	5,176us-gaap_GeneralAndAdministrativeExpense
Changes in fair value of contingent consideration payable	1,000	505
Restructuring charges	10us-gaap_RestructuringCharges	(8)us-gaap_RestructuringCharges
Depreciation	508us-gaap_Depreciation	412us-gaap_Depreciation
Total operating expenses	24,058us-gaap_OperatingExpenses	16,077us-gaap_OperatingExpenses
Loss from operations	(24,058)us-gaap_OperatingIncomeLoss	(15,621)us-gaap_OperatingIncomeLoss
Other income (expenses):
Interest income	171us-gaap_InvestmentIncomeInterest	42us-gaap_InvestmentIncomeInterest
Interest expense	(372)us-gaap_InterestExpense	(355)us-gaap_InterestExpense
Other expense	(29)us-gaap_OtherNonoperatingIncomeExpense	(9)us-gaap_OtherNonoperatingIncomeExpense
Net loss	$ (24,288)us-gaap_NetIncomeLoss	$ (15,943)us-gaap_NetIncomeLoss
Net loss attributable to common stockholders per common share - basic and diluted	$ (0.25)us-gaap_EarningsPerShareBasicAndDiluted	$ (0.25)us-gaap_EarningsPerShareBasicAndDiluted
Weighted-average common shares outstanding - basic and diluted	95,743,416	64,353,952

This element represents reimbursements for research and development costs under collaboration agreements.

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Amount of increase (decrease) in the value of a contingent consideration liability, including, but not limited to, differences arising upon settlement.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Amount of the cost of borrowed funds accounted for as interest expense.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.

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The costs incurred in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, excluding in-process research and development acquired in a business combination consummated during the period. Excludes software research and development, which has a separate concept.

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

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Average number of shares or units issued and outstanding that are used in calculating basic and diluted earnings per share (EPS).

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