Cymabay Therapeutics (CBAY) 10-K31 Mar 142013 FY Annual reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
Document and Entity Information (USD $)	Dec. 31, 2013	Mar. 03, 2014	Jun. 30, 2013
Document And Entity Information [Abstract]	'	'	'
Document Type	'10-K	'	'
Amendment Flag	'false	'	'
Document Period End Date	31-Dec-13	'	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'
Trading Symbol	'CYMA	'	'
Entity Registrant Name	'CymaBay Therapeutics, Inc.	'	'
Entity Central Index Key	'0001042074	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Entity Filer Category	'Smaller Reporting Company	'	'
Entity Common Stock, Shares Outstanding	'	10,064,495	'
Entity Public Float	'	'	$0

Balance_Sheets

Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets:	'	'
Cash and cash equivalents	$24,401	$7,726
Marketable securities	6,843	'
Contract receivables	110	108
Accrued interest receivable	68	9
Prepaid expenses	364	147
Other current assets	453	'
Total current assets	32,239	7,990
Property and equipment, net	3	84
Other assets	258	42
Total assets	32,500	8,116
Current liabilities:	'	'
Accounts payable	697	657
Accrued liabilities	2,251	990
Warrant liability	6,466	'
Facility loan	38	'
Convertible notes	'	13,737
Accrued interest payable	36	2,566
Total current liabilities	9,488	17,950
Facility loan, less current portion	4,407	'
Other liabilities	9	36
Total liabilities	13,904	17,986
Commitments and contingencies	'	'
Redeemable convertible preferred stock, $0.0001 par value: no shares authorized, issued or outstanding at December 31, 2013; 55,258,608 shares authorized and 661,059 shares issued and outstanding at December 31, 2012; aggregate liquidation preference $256,750 as of December 31, 2012	'	318,697
Stockholders' equity (deficit):	'	'
Preferred stock, $0.0001 par value: 10,000,000 shares authorized at December 31, 2013; no shares authorized at December 31, 2012; no shares issued and outstanding	'	'
Common stock, $0.0001 par value: 100,000,000 shares authorized; 9,455,064 and 5,792 shares issued and outstanding as of December 31, 2013 and 2012, respectively	1	'
Additional paid-in capital	367,435	913
Accumulated other comprehensive income	2	'
Accumulated deficit	-348,842	-329,480
Total stockholders' equity (deficit)	18,596	-328,567
Total liabilities and redeemable convertible preferred stock and stockholders' equity (deficit)	$32,500	$8,116

Balance_Sheets_Parenthetical

Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]	'	'
Redeemable convertible preferred stock, par value	$0.00	$0.00
Redeemable convertible preferred stock, shares authorized	0	55,258,608
Redeemable convertible preferred stock, shares issued	0	661,059
Redeemable convertible preferred stock, shares outstanding	0	661,059
Redeemable convertible preferred stock, aggregate liquidation preference	'	$256,750
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	10,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	9,455,064	5,792
Common stock, shares outstanding	9,455,064	5,792

Statements_of_Operations_and_C

Statements of Operations and Comprehensive Loss (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]	'	'
Contract revenue	$0	$3,050
Operating expenses:	'	'
Research and development	4,525	9,280
General and administrative	4,871	4,208
Total operating expenses	9,396	13,488
Loss from operations	-9,396	-10,438
Other income (expense):	'	'
Interest income	10	22
Interest expense	-822	-841
Other income, net	135	2
Net loss	-10,073	-11,255
Net income (loss) attributable to common stockholders	243,994	-23,899
Net loss	-10,073	-11,255
Other comprehensive loss/income:	'	'
Unrealized gains (losses) on marketable securities	2	-2
Other comprehensive income (loss)	2	-2
Comprehensive loss	($10,071)	($11,257)
Basic net income (loss) per common share	$103.52	($4,128.71)
Weighted average common shares outstanding used to calculate basic net income (loss) per common share	2,357,036	5,788
Diluted net loss per common share	($3.54)	($4,128.71)
Weighted average common shares outstanding used to calculate diluted net loss per common share	2,845,609	5,788

Statements_of_Redeemable_Conve

Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (USD $)	Total	Redeemable Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
In Thousands, except Share data	Total	Redeemable Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Balance at beginning of period at Dec. 31, 2011	($304,817)	$306,053	'	$762	$2	($305,581)
Balance at beginning of period (in shares) at Dec. 31, 2011	'	661,059	5,773	'	'	'
Discount conversion feature associated with convertible notes	70	'	'	70	'	'
Issuance of common stock upon exercise of options	'	'	'	'	'	'
Issuance of common stock upon exercise of options (in shares)	'	'	19	'	'	'
Non-employee stock-based compensation expense	1	'	'	1	'	'
Employee and director stock-based compensation expense	80	'	'	80	'	'
Accretion to redemption value of redeemable convertible preferred stock	-12,644	12,644	'	'	'	-12,644
Net loss	-11,255	'	'	'	'	-11,255
Net unrealized gain on marketable securities	-2	'	'	'	-2	'
Balance at end of period at Dec. 31, 2012	-328,567	318,697	'	913	'	-329,480
Balance at end of period (in shares) at Dec. 31, 2012	'	661,059	5,792	'	'	'
Issuance of common stock upon exercise of options	'	'	'	'	'	'
Issuance of common stock upon exercise of options (in shares)	77	'	78	'	'	'
Non-employee stock-based compensation expense	17	'	'	17	'	'
Employee and director stock-based compensation expense	866	'	'	866	'	'
Accretion to redemption value of redeemable convertible preferred stock	-9,289	9,289	'	'	'	-9,289
Repurchase of convertible preferred stock, value	8,247	-8,250	'	8,247	'	'
Repurchase of convertible preferred stock, (in shares)	'	-39,606	'	'	'	'
Conversion of preferred stock to common stock, value	319,736	-319,736	'	319,736	'	'
Conversion of preferred stock to common stock, (in shares)	'	-621,453	2,793,281	'	'	'
Issuance of common stock, net of $5,356 issuance costs	20,712	'	1	20,711	'	'
Issuance of common stock, (in shares)	'	'	6,030,969	'	'	'
Extinguishment of debt through issuance of common stock	16,945	'	'	16,945	'	'
Extinguishment of debt through issuance of common stock, (in shares)	'	'	624,944	'	'	'
Net loss	-10,073	'	'	'	'	-10,073
Net unrealized gain on marketable securities	2	'	'	'	2	'
Balance at end of period at Dec. 31, 2013	$18,596	'	$1	$367,435	$2	($348,842)
Balance at end of period (in shares) at Dec. 31, 2013	'	'	9,455,064	'	'	'

Statements_of_Redeemable_Conve1

Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Statement Of Stockholders Equity [Abstract]	'
Stock issuance cost	$5,356

Statements_of_Cash_Flows

Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Operating activities	'	'
Net loss	($10,073)	($11,255)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'
Depreciation and amortization	55	119
Amortization of notes payable conversion option	10	'
Non-employee stock-based compensation expense	17	1
Employee and director stock-based compensation expense	875	80
Amortization of premium on marketable securities	48	'
Non-cash interest associated with debt discount accretion	47	60
Change in fair value of warrant liability	494	'
Gain on sale of property and equipment	-632	'
Changes in assets and liabilities:	'	'
Contract receivables	-2	16
Accrued interest receivable	-59	91
Prepaid expenses	-217	87
Other assets	-216	51
Accounts payable	40	-951
Accrued liabilities	499	-291
Accrued interest payable	692	781
Other liabilities	-36	-82
Net cash used in operating activities	-8,458	-11,293
Investing activities	'	'
Proceeds from the sale of property and equipment	658	'
Purchases of marketable securities	-6,933	-2,881
Proceeds from sales of marketable securities	44	13,891
Net cash (used in) provided by investing activities	-6,231	11,010
Financing activities	'	'
Proceeds from facility loan	4,853	'
Proceeds from issuance of common stock and warrants, net of issuance costs	26,514	'
Repurchase of preferred stock	-3	'
Principal payments on equipment loans	'	-12
Net cash provided by (used in) financing activities	31,364	-12
Net increase(decrease) in cash and cash equivalents	16,675	-295
Cash and cash equivalents at beginning of year	7,726	8,021
Cash and cash equivalents at end of year	24,401	7,726
Supplemental disclosure of cash flow information	'	'
Interest paid	74	'
Financing costs in accrued expenses	309	'
Issuance of common stock for debt extinguishment	16,945	'
Issuance of common stock warrants to lenders	479	'
Issuance of common stock warrants	5,493	'
Fair value of forward contract	453	'
Conversion of preferred stock into common stock	$323,155	'

Organization_and_Description_o

Organization and Description of Business	12 Months Ended
Organization and Description of Business	Dec. 31, 2013
Accounting Policies [Abstract]	'
Organization and Description of Business	'
	1. Organization and Description of Business
	CymaBay Therapeutics, Inc., formerly Metabolex, Inc., (the Company) is a biopharmaceutical company focused on developing therapies to treat metabolic and rare diseases with high unmet medical needs. Arhalofenate, the Company’s lead product candidate, is being developed for the treatment of gout. The Company was incorporated in Delaware in October 1988 as Transtech Corporation.
	Since inception, the Company has funded its operations primarily through the sale of convertible preferred stock and common stock, receipts from the exercise of related warrants to purchase preferred stock, the issuance of convertible notes, proceeds from facility loans, and up-front fees, milestones, and research and development funding received under collaboration agreements. The primary uses of funds to date have been for research, pre-clinical and clinical development, drug manufacturing, license payments, business development and administration, and spending on capital items.
	The Company is an emerging growth company. Under the JOBS Act emerging growth companies can delay adopting new or revised accounting standards until such time of those standards apply to private companies. The Company has adopted this exemption from new or revised accounting standards, and therefore, it may not be subject to the same new or revised accounting standards as other public companies that are not “emerging growth companies.”
	Liquidity
	The accompanying financial statements for the years ended December 31, 2013 and 2012, have been prepared on a going concern basis, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business for the foreseeable future. The Company has incurred net losses from operations since its inception and has an accumulated deficit of $348.8 million as of December 31, 2013. The Company recorded net losses of $10.1 million and $11.3 million for the years ended December 31, 2013 and 2012, respectively. The Company also recorded negative cash flows from operating activities during 2013 and 2012 of $8.5 million and $11.3 million, respectively. To date, none of the Company’s product candidates have been approved for marketing and sale, and the Company has not recorded any product sales. Management expects operating losses to continue for the next several years. The Company’s ability to achieve profitability is dependent primarily on its ability to successfully develop, acquire or in-license additional product candidates, continue clinical trials for product candidates currently in clinical development, obtain regulatory approvals, and support commercialization activities for partnered product candidates. Products developed by the Company will require approval of the U.S. Food and Drug Administration (FDA) or a foreign regulatory authority prior to commercial sale. The regulatory approval process is expensive, time-consuming, and uncertain, and any denial or delay of approval could have a material adverse effect on the Company. Even if approved, the Company’s products may not achieve market acceptance and will face competition from both generic and branded pharmaceutical products.
	In 2013, in order to address immediate capital requirements, the Company entered into a series of financing transactions. Specifically, on September 30, 2013, all of the shares of the Company’s outstanding redeemable convertible preferred stock converted to common stock and the Company issued shares of common stock and warrants to purchase shares of common stock in a private placement for gross proceeds of $26.8 million. The Company raised an additional $5.0 million in venture debt financing pursuant to a $10.0 million loan agreement, resulting in aggregate net proceeds to CymaBay of $28.8 million after deducting placement agent fees and offering expenses. Also on September 30, 2013, the Company issued shares of common stock in cancellation of approximately $16.9 million of debt owed to the lender. On October 31, 2013, the Company sold additional shares of common stock and warrants to purchase shares of common stock, which sales are also part of the private placement, for net proceeds to CymaBay of $2.2 million after deducting placement agent fees and estimated offering expenses. Further, on November 22, 2013, the Company entered into an agreement with investors to purchase shares of common stock and warrants to purchase shares of common stock as part of the private placement for net proceeds of $2.7 million, which sales occurred shortly after the listing of the Company’s common stock on the over-the-counter market on January 24, 2014. Collectively, the private placement, the venture debt financing and the issuance of our common stock in cancellation of the $16.9 million of debt is referred to as the 2013 financing.
	As of December 31, 2013, the Company had cash and cash equivalents of $24.4 million and marketable securities of $6.8 million. Although these amounts are expected to fund the Company’s ongoing operations through the second quarter of 2015, the Company will require additional financial resources to fund its operations beyond that date, which management plans to raise primarily through equity and/or debt financings and/or collaboration activities. Such funding may not be available to the Company on acceptable terms, or at all. If the Company is not able to secure adequate funding, it may be forced to make reductions in spending, liquidate assets where possible, and/or suspend or curtail planned programs. The accompanying financial statements do not include any adjustments relating to the recoverability of the carrying amounts of recorded assets or the amount of liabilities that might result from the outcome of uncertainties.
	1. Organization and Description of Business
	CymaBay Therapeutics, Inc., formerly Metabolex, Inc., (the Company) is a biopharmaceutical company focused on developing therapies to treat metabolic and rare diseases with high unmet medical needs. Arhalofenate, the Company’s lead product candidate, is being developed for the treatment of gout. The Company was incorporated in Delaware in October 1988 as Transtech Corporation.
	Since inception, the Company has funded its operations primarily through the sale of convertible preferred stock and common stock, receipts from the exercise of related warrants to purchase preferred stock, the issuance of convertible notes, proceeds from facility loans, and up-front fees, milestones, and research and development funding received under collaboration agreements. The primary uses of funds to date have been for research, pre-clinical and clinical development, drug manufacturing, license payments, business development and administration, and spending on capital items.
	The Company is an emerging growth company. Under the JOBS Act emerging growth companies can delay adopting new or revised accounting standards until such time of those standards apply to private companies. The Company has adopted this exemption from new or revised accounting standards, and therefore, it may not be subject to the same new or revised accounting standards as other public companies that are not “emerging growth companies.”
	Liquidity
	The accompanying financial statements for the years ended December 31, 2013 and 2012, have been prepared on a going concern basis, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business for the foreseeable future. The Company has incurred net losses from operations since its inception and has an accumulated deficit of $348.8 million as of December 31, 2013. The Company recorded net losses of $10.1 million and $11.3 million for the years ended December 31, 2013 and 2012, respectively. The Company also recorded negative cash flows from operating activities during 2013 and 2012 of $8.5 million and $11.3 million, respectively. To date, none of the Company’s product candidates have been approved for marketing and sale, and the Company has not recorded any product sales. Management expects operating losses to continue for the next several years. The Company’s ability to achieve profitability is dependent primarily on its ability to successfully develop, acquire or in-license additional product candidates, continue clinical trials for product candidates currently in clinical development, obtain regulatory approvals, and support commercialization activities for partnered product candidates. Products developed by the Company will require approval of the U.S. Food and Drug Administration (FDA) or a foreign regulatory authority prior to commercial sale. The regulatory approval process is expensive, time-consuming, and uncertain, and any denial or delay of approval could have a material adverse effect on the Company. Even if approved, the Company’s products may not achieve market acceptance and will face competition from both generic and branded pharmaceutical products.
	In 2013, in order to address immediate capital requirements, the Company entered into a series of financing transactions. Specifically, on September 30, 2013, all of the shares of the Company’s outstanding redeemable convertible preferred stock converted to common stock and the Company issued shares of common stock and warrants to purchase shares of common stock in a private placement for gross proceeds of $26.8 million. The Company raised an additional $5.0 million in venture debt financing pursuant to a $10.0 million loan agreement, resulting in aggregate net proceeds to CymaBay of $28.8 million after deducting placement agent fees and offering expenses. Also on September 30, 2013, the Company issued shares of common stock in cancellation of approximately $16.9 million of debt owed to the lender. On October 31, 2013, the Company sold additional shares of common stock and warrants to purchase shares of common stock, which sales are also part of the private placement, for net proceeds to CymaBay of $2.2 million after deducting placement agent fees and estimated offering expenses. Further, on November 22, 2013, the Company entered into an agreement with investors to purchase shares of common stock and warrants to purchase shares of common stock as part of the private placement for net proceeds of $2.7 million, which sales occurred shortly after the listing of the Company’s common stock on the over-the-counter market on January 24, 2014. Collectively, the private placement, the venture debt financing and the issuance of our common stock in cancellation of the $16.9 million of debt is referred to as the 2013 financing.
	As of December 31, 2013, the Company had cash and cash equivalents of $24.4 million and marketable securities of $6.8 million. Although these amounts are expected to fund the Company’s ongoing operations through the second quarter of 2015, the Company will require additional financial resources to fund its operations beyond that date, which management plans to raise primarily through equity and/or debt financings and/or collaboration activities. Such funding may not be available to the Company on acceptable terms, or at all. If the Company is not able to secure adequate funding, it may be forced to make reductions in spending, liquidate assets where possible, and/or suspend or curtail planned programs. The accompanying financial statements do not include any adjustments relating to the recoverability of the carrying amounts of recorded assets or the amount of liabilities that might result from the outcome of uncertainties.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2013
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	2. Summary of Significant Accounting Policies
	Basis of Presentation and Use of Estimates
	The financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP), which requires management to make informed estimates and assumptions that impact the amounts and disclosures reported in the financial statements and accompanying notes. Management bases its estimates on historical experience and on assumptions believed to be reasonable under the circumstances. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Actual results could differ materially from those estimates. The Company believes significant judgment is involved in determining revenue recognition and in estimating stock-based compensation, clinical trial accruals, and equity instrument valuations.
	Reverse Stock Split
	On September 30, 2013, the Company filed amended and restated certificates of incorporation under which the Company’s preferred stock and common stock was reverse split on a 1-for-79.5 basis. The accompanying financial statements and notes to the financial statements, other than with respect to the authorized number of shares, give retroactive effect to the reverse split for all periods presented.
	Reclassification of Prior Period Balances
	Certain reclassifications have been made to prior period amounts to conform to current-year presentation.
	Fair Value of Financial Instruments
	The Company’s financial instruments consist of cash and cash equivalents, short-term marketable securities, accounts payable, accrued expenses, warrant liabilities, forward contracts, and convertible notes. Fair value estimates of these instruments are made at a specific point in time, based on relevant market information. These estimates may be subjective in nature and involve uncertainties and matters of significant judgment and therefore cannot be determined with precision. The carrying amounts of cash and cash equivalents, accounts payable and accrued expenses are generally considered to be representative of their respective fair values because of the short-term nature of those instruments.
	Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. Assets and liabilities that are measured at fair value are reported using a three-level fair value hierarchy that prioritizes the inputs used to measure fair value. This hierarchy maximizes the use of observable inputs and maximizes the use of unobservable inputs and is as follows:
	Level 1—Quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.
	Level 2—Inputs other than quoted prices in active markets that are observable for the asset or liability, either directly or indirectly.
	Level 3—Inputs that are unobservable for the asset or liability.
	The following table presents the fair value of the Company’s financial assets and liabilities using the above input categories (in thousands):


			As of December 31, 2013
	Description		Level 1			Level 2		Level 3		Fair Value
	Money market funds		$	21,097		$	—	$	—	$	21,097
	Corporate debt and asset backed securities			—			6,843		—		6,843

	Total assets measured at fair value		$	21,097		$	6,843	$	—	$	27,940

	Forward contract		$	—		$	—	$	453	$	453
	Warrant liability			—			—		6,466		6,466

	Total liabilities measured at fair value		$	—		$	—	$	6,919	$	6,919

	Marketable securities consist of available-for-sale securities that are reported at fair value, with the related unrealized gains and losses included in accumulated other comprehensive income (loss), a component of stockholders’ equity (deficit). The Company values cash equivalents and marketable securities using quoted market prices or alternative pricing sources and models utilizing observable market inputs and, as such, classifies cash equivalents and marketable securities within Level 1 or Level 2.
	As of December 31, 2013, the Company held a Level 3 liability associated with warrants, issued in connection with the Company’s equity offerings, completed in September and October 2013. The warrants are considered liabilities and are valued using an option-pricing model, the significant unobservable inputs for which include exercise price of the warrants, market price of the underlying common shares, expected term, volatility based on a group of the Company’s peers and the risk-free rate corresponding to the expected term of the warrants. As of December 31, 2013, the Company also held a Level 3 liability associated with a forward contract which arose in connection with the Company’s November 22, 2013 execution of an equity purchase agreement with certain investors. The agreement required the Company to issue a fixed number of shares of common stock and warrants to purchase common stock at a predetermined price of $3.0 million provided the Company completes the listing of its common stock on a public stock exchange. The forward contract’s fair value was determined upon execution as the difference between the present value of the equity proceeds to be received under the agreement less the fair value of the underlying securities. The forward contract liability is presented in the balance sheet as a component of accrued liabilities and is revalued at each reporting period until the contract is settled which occurred on January 29, 2014. The fair value of the underlying common stock and warrants were valued using an option-pricing model, the inputs of which are similar to those used in the valuation of the Company’s liability classified warrants. Changes to any of the inputs to the option-pricing models used by the Company can have a significant impact to the estimated fair value of the warrants and forward contract liabilities. As of December 31, 2012, the Company had no assets or liabilities measured at fair value on a recurring basis within the Level 3 hierarchy.

	The following table sets forth a summary of the changes in the fair value of our Level 3 financial instruments (in thousands):


			Warrant			Forward
			Liability			Contract
	Balance as of December 31, 2012		$	—		$	—
	Issuance of financial instrument			5,972			453
	Change in fair value			494			—

	Balance as of December 31, 2013		$	6,466		$	453

	The gains and losses from remeasurement of Level 3 financial liabilities are recorded through other income, net on the accompanying statements of operations and comprehensive loss.
	Cash, Cash Equivalents, and Marketable Securities
	The Company considers all highly liquid investments with a remaining maturity of 90 days or less at the time of purchase to be cash equivalents. Cash and cash equivalents consist of deposits with commercial banks in checking, interest-bearing, and demand money market accounts. The Company invests excess cash in marketable securities with high credit ratings which are classified in Level 1 and Level 2 of the fair value hierarchy. These securities consist primarily of corporate debt and asset-backed securities and are classified as “available-for-sale.” Management may liquidate any of these investments in order to meet the Company’s liquidity needs in the next year. Accordingly, any investments with accompanying contractual maturities greater than one year from the balance sheet date are classified as short-term in the balance sheet.
	Realized gains and losses from the sale of marketable securities, if any, are calculated using the specific-identification method. Realized gains and losses and declines in value judged to be other-than- temporary are included in interest income or expense in the statements of operations and comprehensive loss. Unrealized holding gains and losses are reported in accumulated other comprehensive loss in the balance sheet. To date, the Company has not recorded any impairment charges on its marketable securities related to other-than-temporary declines in market value. In determining whether a decline in market value is other-than-temporary, various factors are considered, including the cause, duration of time and severity of the impairment, any adverse changes in the investees’ financial condition, and the Company’s intent and ability to hold the security for a period of time sufficient to allow for an anticipated recovery in market value.
	Restricted Cash
	The Company is required to maintain compensating cash balances with financial institutions that provide the Company with its corporate credit cards. As of December 31, 2013 and 2012, cash restricted under these arrangements was $155,000 and none, respectively. These amounts are presented in other assets on the accompanying balance sheets.
	Concentration of Credit Risk
	Cash, cash equivalents, and marketable securities consist of financial instruments that potentially subject the Company to a concentration of credit risk to the extent of the fair value recorded in the balance sheet. The Company invests cash that is not required for immediate operating needs primarily in highly liquid instruments that bear minimal risk. The Company has established guidelines relating to the quality, diversification, and maturities of securities to enable the Company to manage its credit risk.
	Property and Equipment
	Property and equipment is carried at cost, less accumulated depreciation and amortization. Depreciation and amortization is calculated using the straight-line method, and the cost is amortized over the estimated useful lives of the respective assets, generally three to seven years. Leasehold improvements are amortized over the shorter of the useful lives or the non-cancelable term of the related lease. Maintenance and repair costs are charged as expense in the statements of operations and comprehensive loss as incurred.
	Impairment of Long-Lived Assets
	The Company reviews long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment loss is recognized if the estimated undiscounted future cash flow expected to result from the use and eventual disposition of an asset is less than the carrying amount. While the Company’s current and historical operating losses and cash flows are indicators of impairment, the Company believes the future cash flows to be received support the carrying value of its long-lived assets. Accordingly, the Company has not recognized any impairment losses as of December 31, 2013 and 2012.
	Deferred Rent
	The Company records its costs under facility operating lease agreements as rent expense. Rent expense is recognized on a straight-line basis over the non-cancelable term of the operating lease. The difference between the actual amounts paid and amounts recorded as rent expense is recorded to deferred rent in the accompanying balance sheets.
	Revenue Recognition
	The Company recognizes revenue when (i) persuasive evidence of an arrangement exists, (ii) delivery has occurred or services have been rendered, (iii) the price is fixed and determinable, and (iv) collectability is reasonably assured. Payments received in advance of work performed are recorded as deferred revenue and recognized when earned. All revenue recognized to date under collaboration agreements has been nonrefundable.
	In 2012, contract revenue was from two strategic partners. There was no contract revenue recorded for the year ended December 31, 2013.
	Multiple Element Arrangements
	The Company evaluates revenue from agreements that have multiple elements to determine whether the components of the arrangement represent separate units of accounting. Management considers whether components of an arrangement represent separate units of accounting based upon whether certain criteria are met, including whether the delivered element has stand-alone value to the customer. To date, all of the Company’s collaboration agreements have been assessed to have one unit of accounting. Up-front and license fees received for a combined unit of accounting have been deferred and recognized ratably over the projected performance period. Non-refundable fees where the Company has no continuing performance obligations have been recognized as revenue when collection is reasonably assured and all other revenue recognition criteria have been met.
	Milestones and Contingent Payments
	Contingent consideration received from the achievement of a substantive milestone will be recognized in its entirety in the period in which the milestone is achieved. A milestone is defined as an event having all of the following characteristics: (i) there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved, (ii) the event can only be achieved based in whole or in part on either the company’s performance or a specific outcome resulting from the company’s performance and (iii) if achieved, the event would result in additional payments being due to the Company.
The Company’s future research and development and license agreements may provide for success fees or payments to be paid to the Company upon the achievement of certain development milestones. Given the challenges inherent in developing biologic products, there may be substantial uncertainty as to whether any such milestones would be achieved at the time the agreements are executed. In addition, the Company will evaluate whether the development milestones meet all of the conditions to be considered substantive. The conditions include: (1) the consideration is commensurate with either of the following: (a) the Company’s performance to achieve the milestone or (b) the enhancement of the value of the delivered item or items as a result of a specific outcome resulting from the Company’s performance to achieve the milestone; (2) the consideration relates solely to past performance; and (3) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. If the Company considers the development milestones to be substantive, revenue related to such future milestone payments will be recognized as the Company achieves each milestone. Research and development funding internal and external research and development costs reimbursed in connection with research and development funding or collaboration agreements are recognized as revenue in the same period as the costs are incurred, and are presented on a gross basis because the Company acts as a principal, has the discretion to choose suppliers, bears credit risk, and performs part of the services.
Research and Development Expenses
Research and development expenses consist of costs incurred in identifying, developing, and testing product candidates. These expenses consist primarily of costs for research and development personnel, including related stock-based compensation; contract research organizations and other third parties that assist in managing, monitoring, and analyzing clinical trials; investigator and site fees; laboratory services; consultants; contract manufacturing services; non-clinical studies, including materials; and allocated expenses, such as depreciation of assets, and facilities and information technology that support research and development activities. Research and development costs are expensed as incurred, including expenses that may or may not be reimbursed under research and development funding arrangements. Research and development expenses under collaboration agreements approximate the revenue recognized under such agreements.
The expenses related to clinical trials are based upon estimates of the services received and efforts expended pursuant to contracts with research institutions and clinical research organizations (CROs) that conduct and manage clinical trials on behalf of the Company. The Company’s objective is to reflect the appropriate trial expenses in its financial statements by matching those expenses with the period in which services and efforts are incurred. Expenses related to clinical trials are accrued based upon the level of activity incurred under each contract as indicated by such factors as progress made against specified milestones or targets in each period, patient enrollment levels, and other trial activities as reported by CROs. Accordingly, the Company’s clinical trial accrual is dependent upon the timely and accurate reporting of expenses by clinical research organizations and other third-party vendors. Payments made to third parties under these clinical trial arrangements in advance of the receipt of the related services are recorded as prepaid assets, depending on the terms of the agreement, until the services are rendered.
Stock-Based Compensation
Employee and director stock-based compensation is measured at the grant date, based on the fair-value-based measurements of the stock awards, and the portion that is ultimately expected to vest is recognized as an expense over the related vesting periods, net of estimated forfeitures. The Company calculates the fair-value-based measurements of options using the Black-Scholes valuation model and recognizes expense using the straight-line attribution method.
Equity awards granted to non-employees are accounted for using the Black-Scholes valuation model to determine the fair value-based measurements of such instruments. The fair value-based measurements of options and warrants granted to non-employees are re-measured over the related vesting period and amortized to expense as earned.
Common Stock Warrants
The Company’s outstanding common stock warrants issued in with the 2013 financing are classified as liabilities in the accompanying balance sheets as they contain provisions that could require the Company to settle the warrants in cash. The warrants were recorded at fair value using either the Black-Scholes option pricing model, probability weighted expected return model or a binomial model, depending on the characteristics of the warrants. The fair value of these warrants is re-measured at each financial reporting period with any changes in fair value being recognized as a component of other income (expense) in the accompanying statements of operations and comprehensive loss.
Income Taxes
The Company utilizes the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on differences between the financial reporting and the tax bases of assets and liabilities and are measured using enacted tax rates and laws that will be in effect when the differences are expected to reverse. A valuation allowance is recorded when it is more likely than not that all or part of a deferred tax asset will not be realized.
The accounting guidance for uncertainty in income taxes prescribes a recognition threshold and measurement attribute criteria for the financial recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination based on the technical merits of the position.
The Company records interest related to income taxes, if any, as interest, and any penalties would be recorded as other expense in the statements of operations and comprehensive loss. There was no interest or penalties related to income taxes recorded during the years ended December 31, 2013 and 2012.
Comprehensive Loss
Comprehensive loss includes net loss and net unrealized gains and losses on marketable securities, which are presented in a single continuous statement. Comprehensive loss is disclosed in the statements of convertible preferred stock and stockholders’ deficit, and is stated net of related tax effects, if any.
Net Income (Loss) Per Common Share
Basic net income (loss) per share of common stock is based on the weighted average number of shares of common stock outstanding equivalents during the period. Prior to the 2013 financing, in addition to common stock, the Company had redeemable convertible preferred stock outstanding that contractually entitled the holder to participate in dividends and earnings of the Company. Accordingly, the Company applied the two-class method for calculating net income (loss) per share. Under this method, all undistributed earnings were allocated first to the preferred stockholders based on their contractual right to dividends. This right was calculated on a pro rated basis for the portion of the period the preferred shares were outstanding. In addition, in connection with the 2013 financing, during the year ended December 31, 2013, the Company converted all outstanding redeemable convertible preferred stock into common stock. The excess of the carrying amount of such redeemable convertible preferred stock over the fair value of the consideration paid to the holders was treated as an adjustment that reduced preferred stockholders’ dividend or distribution entitlement. The amount of earnings that resulted from adjusting net loss for the period as described above was allocated between weighted average number of participating preferred and common stock shares based on their entitlement to such distributions as if all of the earnings of the period had been distributed.
Diluted net loss per share of common stock is calculated using the more dilutive of the two approaches: one, “as-converted” method, under which the weighted average number of common stock shares outstanding during the period is adjusted to include the assumed conversion of redeemable convertible preferred stock at the beginning of the period, and the other, the “two-class” method as described above. Under either approach, the weighted average number of shares outstanding is also adjusted to include the assumed exercises of stock options and warrants, if dilutive. For periods in which the Company has basic net loss per share of common stock, such as for the years ended December 31, 2013 and 2012, diluted net loss per share is the same as basic, as any adjustments would have been anti-dilutive. For the year ending December 31, 2013, the Company’s diluted net loss per common share was calculated using the “as-converted” method, as it resulted in a net loss per share of common stock and accordingly, was more dilutive than the “two-class” method.
In all periods presented, the Company’s outstanding stock options and warrants were excluded from the calculation of earnings (loss) per share because the effect would be antidilutive.
The following table sets forth the computation of basic and diluted net income (loss) per share (in thousands, except share and per share amounts):


		Year Ended December 31,
		2013			2012
Basic:
Numerator:
Net loss		$	(10,073	)	$	(11,255	)
Accretion to redemption value of redeemable convertible preferred stock			(9,289	)		(12,644	)
Reduction in redeemable convertible preferred stock distribution entitlement upon extinguishment			313,933			—
Amounts allocated to participating redeemable convertible preferred stock			(50,577	)		—

Net income (loss) allocated to common stock—basic		$	243,994		$	(23,899	)

Denominator:
Weighted average number of common stock shares outstanding			2,357,036			5,788

Net income (loss) per share—basic:		$	103.52		$	(4,128.71	)
Diluted:
Numerator:
Net income (loss) allocated to common stock		$	243,994		$	(23,899	)
Adjustments from assumed conversion of redeemable convertible preferred stock			(254,067	)		—

Net loss allocated to common stock—diluted		$	(10,073	)	$	(23,899	)

Denominator:
Weighted average number of common stock shares outstanding			2,357,036			5,788
Weighted average number of preferred stock shares outstanding			488,573			—

Total common stock shares equivalents			2,845,609			5,788

Net loss per share—diluted:		$	(3.54	)	$	(4,128.71	)
The following table shows the total outstanding securities considered anti-dilutive and therefore excluded from the computation of diluted net income (loss) per share (in thousands):


		Year ended
		December 31,
		2013			2012
Warrants for common stock			1,743			28
Common stock options			577			104
Redeemable convertible preferred stock			—			661

Marketable_Securities

Marketable Securities	12 Months Ended
Marketable Securities	Dec. 31, 2013
Cash And Cash Equivalents [Abstract]	'
Marketable Securities	'
	3. Marketable Securities
	Marketable available-for-sale securities as of December 31, 2013 consist of the following (in thousands):


		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair Value
				Gains		Losses
	As of December 31, 2013:
	Corporate debt securities	$	6,355	$	3	$	(2	)	$	6,356
	Asset-backed securities		486		1		—			487

		$	6,841	$	4	$	(2	)	$	6,843

	As of December 31, 2013, the Company’s corporate debt marketable securities had contractual maturities of less than one year and asset-backed securities had contractual maturities between 2-5 years. Realized gains and losses were immaterial for the years ended December 31, 2013 and 2012. None of these investments have been in a continuous unrealized loss position for more than 12 months as of December 31, 2013. The company did not hold any marketable securities as of December 31, 2012.

Certain_Balance_Sheet_Items

Certain Balance Sheet Items	12 Months Ended
Certain Balance Sheet Items	Dec. 31, 2013
Organization Consolidation And Presentation Of Financial Statements [Abstract]	'
Certain Balance Sheet Items	'
	4. Certain Balance Sheet Items
	Property and equipment consists of the following (in thousands):


		December 31,
		2013			2012
	Laboratory equipment	$	—		$	3,778
	Office and computer equipment		556			983
	Purchased software		166			166
	Furniture and fixtures		42			174
	Leasehold improvements		2,534			2,534

	Total		3,298			7,635
	Less accumulated depreciation and amortization		(3,295	)		(7,551	)

	Property and equipment, net	$	3		$	84

	Property and equipment includes assets financed through equipment loans, which were fully paid in January 2012.
	Accrued liabilities consist of the following (in thousands):


		December 31,
		2013			2012
	Accrued compensation	$	518		$	291
	Accrued pre-clinical and clinical trial expenses		418			304
	Accrued professional fees		782			285
	Forward contract		453			—
	Other accruals		80			110

	Total accrued liabilities	$	2,251		$	990

Collaboration_Agreements

Collaboration Agreements	12 Months Ended
Collaboration Agreements	Dec. 31, 2013
Organization Consolidation And Presentation Of Financial Statements [Abstract]	'
Collaboration Agreements	'
	5. Collaboration Agreements
	Sanofi-Aventis Deutschland GMBH
	In June 2010, the Company entered into a development and license agreement effective July 21, 2010, with Sanofi-Aventis Deutschland GMBH (Sanofi-Aventis), whereby Sanofi-Aventis received an exclusive worldwide license for the research, development, manufacture and commercialization of small molecules that modulate the G-protein coupled receptor 119 (GPR119). The agreement includes rights to MBX-2982, a potent selective orally active GPR119 agonist discovered by the Company. Upon the effective date of this agreement, the Company received a one-time nonrefundable up-front license payment of $25.0 million. The Company was eligible to receive milestones if certain development and commercial events were achieved, as well as royalties on worldwide product sales, if any. The one-time nonrefundable up-front license payment was being recognized as revenue ratably over the period that the Company expected to complete certain research and development activities that represent the Company’s substantive performance obligations under the agreement. Of this up-front license fee, none was recognized for the years ended December 31, 2013 or December 31, 2012.
	On June 15, 2011, the arrangement was terminated by Sanofi-Aventis. Following termination, the Company retained rights to the current programs under this agreement and may continue to develop the programs and commercialize any products resulting from the programs, or the Company may elect to cease progressing the programs and/or seek other partners for further development and commercialization of the programs.
	In 2012, the Company recognized a final payment from Sanofi-Aventis of $2.9 million as contract revenue.

	Takeda San Francisco, Inc.
	In March 2010, the Company entered into a research collaboration agreement with Takeda San Francisco, Inc. (TSF), a wholly owned subsidiary of Takeda Pharmaceutical Company Limited. The Company collaborated with TSF on the evaluation and validation of protein targets for the development of biological products. In March 2010, the Company received $1.5 million, representing $0.9 million of one-time nonrefundable technology access fees and $0.6 million of specified research and development funding for the research term of the collaboration. The technology access fee and the research and development funding were deferred and were being recognized ratably over the funded research term, which was scheduled from March 2010 to August 2011. Approximately $0.1 was recognized as specific research and development funding under this agreement in the year ended December 31, 2012. Takeda terminated this agreement on March 16, 2013 with no further payments being made as of the year ended December 31, 2013.
	Pfizer, Inc.
	In December 1998, the Company entered into a collaboration agreement in the area of insulin secretion target discovery with the Parke-Davis division of Warner-Lambert Company, since acquired by Pfizer Inc., to identify genes involved in diabetes and to develop therapeutic compounds from the research. The collaboration agreement provided for an initial five-year funded research term, which was subsequently extended an additional year until December 2004. The Company received payments for research and development costs for the funded research term and is entitled to receive payments for specified drug development achievements. If products resulting from the collaboration are eventually marketed and sold, the Company will also receive royalties on sales of such products. No amounts were received under this agreement in the years ended December 31, 2013 and, 2012.
	The Company was also eligible to receive contingent payments if certain development and commercial events were achieved as well as royalties on worldwide product sales, if any. No amounts were received under this agreement for the years ended December 31, 2013 and 2012.

License_Agreements

License Agreements	12 Months Ended
License Agreements	Dec. 31, 2013
Goodwill And Intangible Assets Disclosure [Abstract]	'
License Agreements	'
	6. License Agreements
	In June 1998, the Company entered into a license agreement with DiaTex, Inc. (DiaTex) relating to products containing halofenate, its enantiomers, derivatives, and analogs (the licensed products). The license agreement provides that DiaTex and the Company are joint owners of all of the patents and patent applications covering the licensed products and methods of producing or using such compounds, as well as certain other know-how (the covered IP). As part of the license agreement, the Company received an exclusive worldwide license, including as to DiaTex, to use the covered IP to develop and commercialize the licensed products. The Company also retained the right to sub-license the covered IP. The license agreement contains a $2,000 per month license fee as well as a requirement to make additional payments for development achievements and royalty payments on any sales of licensed products. Pursuant to the license agreement, all of the Company’s patents and patent applications related to arhalofenate, its use, and production are jointly owned with DiaTex. DiaTex is entitled to up to $0.8 million for the future development of arhalofenate, as well as royalty payments on any sales of products containing arhalofenate. No development payments were made in the years ended December 31, 2013 and, 2012 and no royalties have been paid to date.

Debt

Debt	12 Months Ended
	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Debt	'
	7. Debt
	JJDC Convertible Note
	On June 20, 2006 the Company entered into a equity and loan facility with the Johnson and Johnson Development Corporation (“JJDC”) pursuant to which the Company could drawn down up to an aggregate of $30 million in loans in the form of convertible preferred stock promissory notes. In March and September 2008, the Company issued notes in the aggregate amount of $3.5 million and $10.5 million, respectively. The notes were due on March 17 and September 17, 2011, including interest that accrued at 7.57% per annum. In December 2010, the aggregate principal amount and all accrued interest under the notes issued in March and September 2008 were converted into the Company’s Series E-3 convertible preferred stock (Series E-3 Preferred) at 232.93 per share.
	In February and July 2009, the Company issued notes in the aggregate amount of $7.0 million and $6.7 million, respectively, in accordance with the terms of the equity and loan facility with JJDC. The notes were due in February 2012 and July 2012, including interest that accrued at 4.42% per annum and 4.960% per annum, respectively. In January 2012, the Company amended the maturity dates of the outstanding $7.0 million and $6.7 million convertible promissory notes to extend the maturity date to March 1, 2013, and interest rates were increased to 4.919% and 5.46% per annum, respectively. In addition, the conversion price of the notes to convert into shares of the Company’s Series C-1 Preferred Stock was decreased from $438.84 per share to $292.56 per share. All of these notes were further amended in March 2013, to extend the maturity date on the notes to August 1, 2013, and to make the notes subordinate to repayment of the Company’s severance obligations to all employees until January 1, 2014. On July 31, 2013, the maturity date was extended to December 31, 2013. For the years ended December 31, 2013 and 2012, the Company recognized $0.6 million and $0.7 million respectively, of interest expense related to the convertible promissory notes. On September 30, 2013, the outstanding principal and accrued interest of $16.9 million under the equity and loan facility with JJDC was extinguished in exchange for the issuance of 624,944 shares of common stock as an integral part of the 2013 finance restructuring.
	Facility Loan
	On September 30, 2013, the Company entered into a facility loan agreement with Silicon Valley Bank and Oxford Finance for a total loan amount of $10.0 million of which the first tranche of $5.0 million was drawn as part of the 2013 financing and bears interest at a rate equal 8.75% per annum. The second tranche of $5.0 million will be made available to the Company only upon achievement of positive Phase 2b data (the second draw milestone) and shall remain available to the Company until June 30, 2015. Loans under the second tranche will bear interest at a rate fixed at the time of borrowing equal to the greater of (i) 8.75% per annum and (ii) the sum of the Wall Street Journal prime rate plus 4.25% per annum.
	For each tranche borrowed, the Company is required to make 12 monthly interest only payments after the funding date followed by a repayment schedule equal to 36 equal monthly payments of interest and principal. After the 36-month amortization period of each tranche, the remaining balance of such tranche and a final payment equal to 6.50% of the original principal amount of the applicable tranche are payable on the maturity date of such tranche. The final payment equal to 6.50% of the original principal is being accreted over the life of the loan.

	Future principal payments due under the loan facility are as follows (in thousands):


		Principal
		Payments
	Year ending December 31:
	2014	$	245
	2015		1,546
	2016		1,687
	2017		1,522

	Total future principal payments due under loan agreement	$	5,000

	During the loan term, the term loan facility provides that the Company must maintain compliance with one of two financial covenants at all times: (1) maintain 1.3 times cash to outstanding debt or (2) maintain sufficient cash on hand to support eight months of operations based on a trailing average monthly cash burn. The term loan facility also contains a series of performance covenants however failure to comply with these performance covenants shall not be an event of default under the term loan facility so long as the Company deposits an amount equal to 100% of the aggregate outstanding term loans in a segregated, blocked deposit account at Silicon Valley Bank. As of December 31, 2013, the Company was in compliance with its loan covenants.
	The Company is permitted to make voluntary prepayments of the term loans with a prepayment fee equal to 3% of the term loans prepaid. The Company is required to make mandatory prepayments of the outstanding term loans upon the acceleration by the lenders of such loans following the occurrence of an event of default, along with a payment of the final payment, the prepayment fee and any all other obligations that are due and payable at the time of the prepayment.
	The Company was required to pay a facility fee of 1.00% on the term loan facility commitment. In addition, at the time of the facility loan drawdown, the Company issued warrants exercisable for a total of 121,739 shares of the Company’s common stock to the lenders at an exercise price of $5.00 per share. As a result of this a warrant liability of $0.5 million was recorded in the accompanying balance sheet as of September 30, 2013. The facility fee, the warrant value on its issuance date, and other debt issuance costs were reflected as a debt discount and are being amortized to interest expense over the term of the outstanding loan using the effective interest rate method. The liability classified warrants must be remeasured at fair value on each reporting date and changes in fair value are recorded as other income, net in the accompanying statement of operations (see Note 11 for more details).

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	8. Commitments and Contingencies
	Operating Lease Commitments
	For the years ended December 31, 2013 and 2012, the Company leased office and laboratory space in a single building in Hayward, California. The facility lease, as amended on July 15, 2010, had a term of four years, unless terminated earlier by the Company, and expires on April 30, 2014. Rent expense was $0.5 million for the years ended December 31, 2013 and 2012. On November 8, 2013, the Company entered into a new lease commencing January 16, 2014, and expiring on December 31, 2018, for 8,894 square feet of office space in Newark, California.

	Future minimum lease payments under operating lease commitments are as follows (in thousands):


		Lease
		Payments
	Year ending December 31:
	2014	$	337
	2015		209
	2016		216
	2017		222
	2018		228

	Total future minimum payments	$	1,212

	Indemnification
	In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnification, including indemnification associated with product liability or infringement of intellectual property rights. The Company’s exposure under these agreements is unknown because it involves future claims that may be made against the Company that may be, but have not yet been, made. To date, the Company has not paid any claims or been required to defend any action related to these indemnification obligations, and no amounts have been accrued in the accompanying balance sheets related to these indemnification obligations.
	The Company has agreed to indemnify its executive officers and directors for losses and costs incurred in connection with certain events or occurrences, including advancing money to cover certain costs, subject to certain limitations. The maximum potential amount of future payments the Company could be required to make under this indemnification is unlimited; however, the Company maintains insurance policies that may limit its exposure and may enable it to recover a portion of any future amounts paid. Assuming the applicability of coverage, the willingness of the insurer to assume coverage, and subject to certain retention, loss limits, and other policy provisions, the Company believes the fair value of these indemnification obligations is not material. Accordingly, the Company has not recognized any liabilities relating to these obligations as of December 31, 2013 and 2012. No assurances can be given that the covering insurers will not attempt to dispute the validity, applicability, or amount of coverage without expensive litigation against these insurers, in which case the Company may incur substantial liabilities as a result of these indemnification obligations.

Redeemable_Convertible_Preferr

Redeemable Convertible Preferred Stock

12 Months Ended

Dec. 31, 2013

Equity [Abstract]

Redeemable Convertible Preferred Stock

9. Redeemable Convertible Preferred Stock

Upon the closing of the 2013 financing on September 30, 2013, all the outstanding shares of the Company’s redeemable convertible preferred stock were converted into 2,793,281 shares of common stock, and the related carrying value of $320.0 million was reclassified to additional paid-in capital. As of December 31, 2013, no shares of redeemable convertible preferred stock were issued or outstanding.

Prior to the September 30, 2013 conversion, the Company had the following series of outstanding convertible preferred stock (collectively, the Preferred Stock): Series A-1 Preferred, Series B-1 Preferred, Series C-1 Preferred, Series D-1 Preferred, Series E-1 Preferred and Series E-3 Preferred. Series E-1 Preferred and Series E-3 Preferred are collectively referred to as the Series E Preferred. The Preferred Stock was initially recorded at its original purchase price, which represented fair value on the date of issuance, net of issuance costs, if any. The original purchase price per share of Series A-1 Preferred, Series B-1 Preferred, Series C-1 Preferred, Series D-1 Preferred, and Series E Preferred was equal to $232.93, $232.93, $365.70, $232.94, and $232.93 per share, respectively. The preferred stock balances were recorded at the original fair value and the accreted dividends based on the per share terms at issuance of Series A-1 Preferred, Series B-1 Preferred, Series C-1 Preferred, Series D-1 Preferred, and Series E Preferred, which were equal to $18.64, $18.64, $29.26, $18.64, and $18.64 per share per annum, respectively.

The shares of Series B-1 Preferred, Series D-1 Preferred, and Series E Preferred were redeemable upon the request of the holders of at least 66 2/3% of outstanding shares of Series B-1 Preferred, voting as a separate class, and 51% of outstanding shares of Series D-1 Preferred and Series E Preferred, voting together as a separate class. In this event, the Company would have been required to redeem the shares in three equal annual installments, beginning in September 2021, at the applicable original purchase price per share. All shares of Preferred Stock were redeemable in the event of a change of control at their liquidation preferences.

As all Preferred Stock was redeemable either at the option of the holder or upon an event outside the control of the Company (i.e., a change in control), the related amounts have been presented outside of stockholders’ equity (deficit). In August and December 2003, the Company completed two closings of a private placement of Series B-1 Preferred, in which the Company issued a total of 136,520 shares at a price of $232.93 per share for gross proceeds of $31.8 million. In November and December 2004, the Company completed two further closings of Series B-1 Preferred, in which the Company issued a total of 188,894 shares at a price of $232.93 per share for gross proceeds of $44.0 million. The Series B-1 Preferred investors in these two final closings also purchased warrants for 29,245 shares of common stock at an exercise price of $30.21 per share, with an exercise period of five years from the date of purchase, for $1.51 cents per share of common stock covered by the warrants. In November 2009, the exercise period of these warrants was extended to December 31, 2011. In December 2012, the Company’s Board of Directors reduced the number of shares exercisable under these warrant by 45% of the original shares and approved the extension of the exercise period until April 1, 2013. As of December 31, 2012, warrants to purchase 13,160 shares of common stock were outstanding. In April 2013, these warrants expired in accordance with their terms.

In August 2006, the Company issued 27,345 shares of Series C-1 Preferred to JJDC at a price of $365.70 per share, for gross proceeds of $10.0 million.

In April 2007, the Company issued 137,592 shares of Series D-1 Preferred at a price of $232.94 per share, for gross proceeds of $32.0 million. In connection with the issuance, the Series D-1 Preferred investors also purchased warrants for an aggregate of 20,639 shares of common stock at an exercise price of $22.13 per share, with an exercise period of five years from the date of purchase, for $0.79 cents per share of common stock covered by the warrants.

In August 2008, the Company repurchased 646, 1,610 and 472 shares of Series A-1 Preferred, Series B-1 Preferred and Series D-1 Preferred, respectively, and a warrant for 71 shares of common stock, for an aggregate purchase price of $82,000. The Company allocated the purchase price among the preferred shares and warrant based upon their respective fair values.

In November 2009, the Company issued 1,288 shares of Series E-1 Preferred upon the conversion of debt issued under a loan agreement. In June and December 2010, the Company issued 859 and 37,119 shares of Series E-1 Preferred, respectively, upon conversion of debt issued under a loan agreement.

In December 2010, the Company issued 71,543 shares of Series E-3 Preferred upon conversion of the JJDC convertible notes that were due in 2011 (Note 7).

As of December 31, 2012, convertible preferred stock balances were as follows (in thousands, except share amounts):

Aggregate

Carrying

Authorized

Issued and

Liquidation

Value

Outstanding

Preference

Series A-1

12,734

5,187

75,454

Series B-1

373,223

146,549

145,408

Series C-1

75,472

27,345

15,122

15,074

Series D-1

136,948

136,949

46,520

43,271

Series E-1

40,252

39,265

19,820

10,674

Series E-3

93,082

71,543

23,552

28,816

Total

731,711

661,059

256,750

318,697

The significant rights, privileges, and preferences of the Preferred Stock were as follows:

Election of Directors

Prior to the September 30, 2013 conversion, the holders of Series B-1 Preferred were entitled to elect five members of the Company’s Board of Directors, the holders of Series D-1 Preferred were entitled to elect one member of the Company’s Board of Directors, and the holders of common stock were entitled to elect one member of the Company’s Board of Directors, subject to certain restrictions. All remaining members of the Company’s Board of Directors were elected by all of the stockholders voting on an as-if-converted basis.

Voting Rights

Prior to the September 30, 2013 conversion, the Preferred Stock carried voting rights equal to the number of shares of common stock into which it could be converted. Additionally, certain corporate actions could only be exercised upon the approval of holders of 66 2/3% of the outstanding shares of Series B-1 Preferred and Series C-1 Preferred, voting together as a single class, and 51% of the outstanding shares of Series D-1 Preferred and Series E Preferred, voting together as a single class.

Dividends

All dividends were payable when and if declared by the Company’s Board of Directors. The holders of Series E Preferred were entitled to cumulative dividends in preference to the holders of Series A-1 Preferred, Series B-1 Preferred, Series C-1 Preferred, Series D-1 Preferred, and common stock. The holders of Series D-1 Preferred were entitled to cumulative dividends in preference to the holders of Series A-1 Preferred, Series B-1 Preferred, Series C-1 Preferred, and common stock. The holders of Series B-1 Preferred and Series C-1 Preferred were entitled to cumulative dividends in preference to the holders of Series A-1 Preferred and common stock. The holders of Series A-1 Preferred were entitled to cumulative dividends in preference to the holders of common stock. The dividend rate was $18.64, $18.64, $29.26, $18.64, and $18.64 per annum for each outstanding share of Series E Preferred, Series D-1 Preferred, Series C-1 Preferred, Series B-1 Preferred, and Series A-1 Preferred, respectively. Additionally, if dividends were paid to any holder of common stock, the holders of Preferred Stock would receive a dividend of a per share amount (on an as-if-converted to common stock basis) equal to the amount paid to the holders of common stock.

No dividends were declared as of December 31, 2013 and 2012. Prior to the conversion of the Preferred Stock in connection with the 2013 financing, the aggregate cumulative dividends as of September 30, 2013, were $3.4 million ($47.28 per share), $1.9 million ($48.14 per share), $15.9 million ($116.00 per share), $5.6 million ($201.83 per share), $63.1 million ($168.96 per share), and $2.3 million ($183.64 per share) for Series E-3 Preferred, Series E-1 Preferred, Series D-1 Preferred, Series C-1 Preferred, Series B-1 Preferred, and Series A-1 Preferred, respectively. The aggregate cumulative dividends as of December 31, 2012, were $2.7 million ($38.04 per share), 1.5 million ($38.90 per share), $14.6 million ($106.75 per share), $5.1 million ($187.32 per share), $59.6 million ($159.72 per share), and $2.2 million ($174.40 per share) for Series E-3 Preferred, Series E-1 Preferred, Series D-1 Preferred, Series C-1 Preferred, Series B-1 Preferred, and Series A-1 Preferred, respectively.

Liquidation Preference

While the Preferred Stock was outstanding, in the event of a liquidation, dissolution, winding up, or change in control of the Company, the liquidation preference of each stockholder class was to be paid in the following order, from available funds: first to the holders of Series E-1 Preferred and Series E-3 Preferred, second to the holders of Series D-1 Preferred, third to the holders of Series B-1 Preferred and Series C-1 Preferred, and fourth to the holders of Series A-1 Preferred. After payment of the Preferred Stock liquidation preferences, the remaining assets of the Company were to be distributed ratably to all holders of common stock and Preferred Stock on an as-if-converted basis. The liquidation preference of Series E-1 Preferred, Series E-3 Preferred, Series D-1 Preferred, Series C-1 Preferred, Series B-1 Preferred, and Series A-1 Preferred was equal to $465.87, $290.97, $232.93, $365.70, $232.93, and $232.93 per share, respectively, plus any cumulative unpaid dividends. If there were insufficient funds available to satisfy each liquidation preference in its entirety, the holders of Preferred Stock were to be paid a pro rata amount based on their liquidation preference.

Conversion Rights

Each share of Preferred Stock was convertible at any time, at the option of the holder, into shares of the Company’s common stock at then applicable conversion rate. The conversion rate for each of the series of Preferred Stock was 1:1, except for the Series D-1 Preferred, which had a conversion rate of 1.365:1. With respect to the Series E Preferred, Series D-1 Preferred, Series B-1 Preferred, and Series A-1 Preferred, if the Company issued common stock or securities convertible into or exercisable for shares of common stock at a price less than the respective original purchase price per share, the conversion rate of such stock was to be adjusted to the lowest price per share paid in such issuance. The conversion rate for Preferred Stock would not be adjusted for common stock issuances on the exercise of options or warrants issued to employees, directors, or consultants of the Company and in certain other circumstances.

Each share of Preferred Stock automatically converted into common stock upon the approval of holders of 66 2/3% of the outstanding shares of Series B-1 Preferred, voting as a separate class, and 51% of the outstanding shares of Series D-1 Preferred and Series E Preferred, voting together as a separate class, or upon the closing of an underwritten public offering of the Company’s common stock pursuant to an effective registration statement under the Securities Act of 1933, as amended, at a per share price of at least $8.00, and raising aggregate gross proceeds of at least $30.0 million. In connection with the 2013 financing each holder of the Company’s preferred stock that participated in the 2013 financing for between 1% and up to 99% of such holders “Pro Rata Share” (as defined in the Company’s then effective certificate of incorporation) had each share of preferred stock represented by such participation amount converted into four shares of common stock and the balance of any shares of preferred stock converted at the then applicable conversion rate. Any holder that participated in the 2013 financing for between 100% and 300% of such holder’s Pro Rata Share (the “Participation Multiple”) had each share of preferred stock convert into shares of common stock by multiplying the product of (y) the aggregate number of shares of preferred stock held by such holder multiplied by the applicable Participation Multiple and (z) four (4).

Common_Stock

Common Stock	12 Months Ended
	Dec. 31, 2013
Equity [Abstract]	'
Common Stock	'
	10. Common Stock
	The Company was authorized to issue 100,000,000 and 74,000,000 shares of common stock as of December 31, 2013 and 2012, respectively.

	Common Stock Issuances in the 2013 Financing
	On September 30, 2013, all the outstanding shares of the Company’s redeemable convertible preferred stock were converted into 2,793,281 shares of common stock and the related carrying value of $320.0 million was reclassified to additional paid-in capital.
	Commencing on September 30, 2013, the Company entered into a series of financing transactions (collectively referred to as the 2013 financing) which resulted in the issuance of common stock and warrants to purchase shares of common stock. Specifically, on September 30, 2013, the Company sold 5,366,669 shares of common stock and 1,073,338 warrants to purchase shares of common stock in a private placement for net proceeds to CymaBay of $22.8 million after deducting placement agent fees and estimated offering expenses. Also on that date, the Company issued 624,944 shares of common stock in cancellation of approximately $16.9 million of debt owed to JJDC, the holder of that debt (Note 7).
	On October 31, 2013, the Company sold an additional 664,300 shares of common stock and warrants to purchase 132,860 shares of common stock, which sales were also part of the private placement, for net proceeds to CymaBay of $2.2 million after deducting placement agent fees and estimated offering expenses.
	On November 22, 2013, the Company entered into an agreement with investors to purchase 604,000 shares of common stock and 120,800 warrants to purchase shares of common stock as part of the private placement for net proceeds of $2.7 million, which sales were set to occur shortly after the listing of the Company’s common stock on the over-the-counter market. Cymabay began trading on the over-the-counter market on January 24, 2014 enabling this portion of the financing to be completed in late January 2014.
	Common Stock Warrants
	In connection with 2013 financing and the Company’s private placement of common stock and warrants, in September and October 2013, the Company issued five-year warrants to purchase 1,620,988 shares of CymaBay’s common stock at an exercise price of $5.75 per share which we refer to here as our 2013 financing warrants. The Company also issued five-year warrants to purchase 121,739 shares of CymaBay’s common stock to its lenders at an exercise price of $5.00 per share. The 2013 financing warrants contain provisions that are contingent on the occurrence of a change in control, which would conditionally obligate the Company to repurchase the warrants for cash in an amount equal to their fair value using the Black-Scholes Option Pricing Model (the “Black-Scholes Model”) on the date of such change in control. Due to these provisions, the Company is required to account for the 2013 financing warrants issued in September and October 2013 as a liability at fair value. In addition, the estimated liability related to the 2013 financing warrants is required to be revalued at each reporting period until the earlier of the exercise of the warrants, at which time the liability will be reclassified to stockholders’ equity, or expiration of the warrants. At issuance date, the fair value of the 2013 financing warrant liability was estimated to be $6.0 million. These warrants were revalued at fair value as of December 31, 2013 using a binomial lattice model and the resulting increase in fair value of $0.5 million was recorded as an increase to the warrant liability and as a loss in other income, net in the Company’s Statement of Operations and Comprehensive Loss.
	In November 2009, the Company’s Board of Directors approved the extension of the time period in which the holders of warrants to purchase 29,245 shares of common stock are able to exercise their warrants that were issued in connection with the issuance of Series B-1 Preferred. The exercise periods of the warrants that originally ended in November 2009 were extended to December 31, 2010. In December 2010, the Company’s Board of Directors further modified these warrants. The number of common shares exercisable under the warrants was reduced by 50% to 14,623, and the exercise period was extended to December 31, 2012. In December 2012, the Company’s Board of Directors again modified these warrants to purchase common stock. The number of shares exercisable under the warrants issued with the issuance of the Series B-1 Preferred was reduced by 45% of the original shares to 13,163, and the exercise period was extended to April 1, 2013. The extension of the agreement did not cause a material change in value. In April 2013, these warrants expired.

	In December 2010, the Company’s Board of Directors modified the warrants to purchase common stock that were issued in connection with the issuance of Series D-1 Preferred. The exercise period of the warrants issued in connection with the Series D-1 Preferred issuance was extended to April 13, 2013. The charge related to the modifications to these warrants of $0.1 million was recorded to accumulated deficit and was determined using the Black-Scholes valuation model, with the following inputs used to determine the charge related to the modification: fair value of the Company’s common stock of $15.90 per share, expected life of the modified warrants of one to two years, risk-free interest rate of 0.50%, and expected common stock price volatility of 83%. In April 2013, these warrants expired.
	Shares of Common Stock Authorized for Issuance
	As of December 31, 2013 and December 31, 2012, the Company had reserved shares of authorized but unissued common stock as follows:


		Shares Reserved		Shares Reserved
		December 31, 2013		December 31, 2012
	Outstanding common stock warrants		1,742,727		28,208
	Equity incentive plans		577,294		140,474
	Convertible preferred stock		—		661,059

	Total reserved shares of common stock		2,320,021		829,741

Stock_Plans_and_StockBased_Com

Stock Plans and Stock-Based Compensation	12 Months Ended
Stock Plans and Stock-Based Compensation	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock Plans and Stock-Based Compensation	'
	11. Stock Plans and Stock-Based Compensation
	Stock Plans
	In September 2013, the Company’s stockholders approved the 2013 Equity Incentive Plan (2013 Plan), under which shares of common stock are reserved for the granting of options, stock bonuses, and restricted stock awards by the Company. These awards may be granted to employees, members of the Board of Directors, and consultants to the Company. The 2013 Plan has a term of ten years and replaced the 2003 Equity Incentive Plan, which had similar terms. The 2013 Plan permits the Company to (i) grant incentive stock options to directors and employees at not less than 100% of the fair value of common stock on the date of grant; (ii) grant nonqualified options to employees, directors, and consultants at not less than 85% of fair value; (iii) award stock bonuses; and (iv) grant rights to acquire restricted stock at not less than 85% of fair value. Options generally vest over a four- or five-year period and have a term of ten years. Options granted to 10% stockholders have a maximum term of five years and require an exercise price equal to at least 110% of the fair value on the date of grant. The exercise price of all options granted to date has been at least equal to the fair value of common stock on the date of grant.
	Restricted stock units, which had been previously granted in 2007 pursuant to the Company’s 2003 Equity Incentive Plan, vested over a four- or five-year period, subject to certain performance conditions, and terminated on August 19, 2012.
	Stock Plan Activity
	In December 2013, the Company’s Board of Directors modified the terms of 60,847 stock options held by employees, directors, and scientific advisory board members. Specifically, the exercise price for such options was reduced to $5, the fair market value of the Company’s common stock on the date of modification, and the term of each option was extended to 10 years from the date of the modification. The Company will account for this stock option modification by recognizing any unamortized expense related to the original unmodified options as of the modification date over the remaining vesting periods of those awards. The incremental expense resulting from this modification of $0.2 million will also be recognized over the remaining vesting period. As substantially all of the modified awards were fully vested on the modification date, the Company recognized $0.2 million of noncash stock-based compensation expense related to this stock option modification in December 2013.

	As of December 31, 2013, 41 shares were available for issuance under the 2013 plan. In accordance with the provisions of the Company’s 2013 Equity Plan, the number of shares available for issuance under the plan automatically increased by 472,753 shares on January 1, 2014.
	The following table summarizes stock option activity:


			Shares				Weighted-			Weighted-		Aggregate
			Subject to				Average			Average		Intrinsic
			Outstanding				Exercise			Remaining		Value (in
			Options				Price of			Contractual		thousands)
							Options			Term
										(Years)
	Outstanding as of December 31, 2012			103,760			$	34.19			4.43	$	—
	Options granted			487,697				5
	Options exercised			(77	)			4.77
	Options forfeited			(3,490	)			10.36
	Options expired			(10,637	)			31.31

	Outstanding as of December 31, 2013			577,253			$	7			9.57	$	3

	Vested and expected to vest as of December 31, 2013			557,995			$	7.07			9.56	$	3

	Exercisable as of December 31, 2013			289,308			$	9.55			9.25	$	1
	The following table summarizes information about stock options outstanding as of December 31, 2013 :


			Options Outstanding							Options Exercisable
	Exercise Price		Number				Weighted-			Number of Shares
			of				Average
			Shares				Remaining
							Contractual
							Term
							(Years)
	$4.77			12,257				7.62			8,815
	$5.00			548,544				9.88			264,041
	$15.90			839				0.27			839
	$30.21			8,638				0.41			8,638
	$39.75			3,520				0.27			3,520
	$238.50			3,455				2.73			3,455

				577,253				9.57			289,308

	Grant Date Fair Value
	The following table presents the weighted-average assumptions the Company used with the Black-Scholes valuation model to derive the grant date fair value-based measurements of employee and director stock options and the resulting estimated weighted-average grant date fair-value-based measurements per share:


			Year Ended December 31,
			2013				2012
	Weighted-average assumptions:
	Expected term			6 yrs				6.25 yrs
	Expected volatility			92	%			100	%
	Risk-free interest rate			1.76	%			1.01	%
	Expected dividend yield			0	%			0	%
	Weighted-average grant date fair value per share		$	3.76			$	3.97

	Expected Term
	The Company does not believe it can currently place reliance on its historical exercise and post-vesting termination activity to provide accurate data for estimating the expected term. Therefore, for stock option grants made during the years ended December 31, 2013 and 2012, the Company has opted to use the simplified method for estimating the expected term which is an average of the contractual term of the options and its ordinary vesting period. The expected term represents the period of time that options are expected to be outstanding.
	Expected Volatility
As the Company does not have any trading history for its common stock, the expected stock price volatility for the Company’s common stock was estimated by considering the volatility rates of similar publicly traded peer entities within the life sciences industry.
Risk-Free Interest Rate
The risk-free interest rate assumption was based on U.S. Treasury instruments with constant maturities whose term was consistent with the expected term of stock options granted by the Company.
Expected Dividend Yield
The Company has never declared or paid cash dividends and does not plan to pay cash dividends in the foreseeable future. Consequently, the Company uses an expected dividend yield of zero.
Common Stock Fair Value
The Company’s Board of Directors has historically determined the fair value of the Company’s common stock for the purpose of pricing the Company’s equity awards to employees, directors, and consultants. As there has been no public market for the Company’s common stock, the Company’s Board of Directors, in making such fair value determinations, considered a number of factors, including the price at which Preferred Stock was issued to outside investors in arm’s-length transactions, the rights, preferences, and privileges of the Preferred Stock relative to the common stock, important developments relating to advancement of the Company’s technology and clinical programs, the Company’s stage of development and business strategy, the likelihood of achieving a liquidity event for the shares of common stock, such as an initial public offering or sale of the Company, prevailing market conditions, and the market prices of various publicly held life sciences companies. Additionally, the Board of Directors considered contemporaneous valuations provided by third-party valuation specialists.
Forfeitures
The Company estimates forfeitures at the time of grant and revises these estimates in subsequent periods if actual forfeitures differ from those estimates. Changes in forfeiture estimates impact compensation in the period in which the change occurs.
The total intrinsic value of options exercised was none for the years ended December 31, 2013 and 2012.
Vested and Unvested Awards
The total fair value of options vested for the years ended December 31, 2013 and 2012, was $0.9 million and $0.1 million, respectively.
As of December 31, 2013, and 2012 the total compensation expense related to unvested employee stock options to be recognized in future periods, excluding estimated forfeitures, was $1.2 million and $0.2 million, respectively. The weighted-average periods over which this compensation expense is expected to be recognized are 3.9 years and 2.0 years as of December 31, 2013 and 2012, respectively.
Incentive Awards
In December 2013, as permitted by the 2013 Equity Plan, the Company issued certain incentive awards to directors, employees and a consultant which are indexed to 220,266 shares of the Company’s common stock and are exercisable at $5 per share when vested. The Company may determine at its option whether to settle exercised awards in shares of common stock or in cash. Each recipient’s incentive award defines the number of common shares that may be acquired upon exercise provided the Company chooses to settle in shares. For awards settled in cash, the Company must pay the recipient the excess of the fair market value of the Company’s common stock on the date of exercise over the $5 exercise price paid by the recipient multiplied by the number of shares the recipient would be entitled to receive had the award been settled in shares of the Company’s common stock.
The incentive awards vest 100% on the second anniversary of their grant date and have a term of 10 years. If before this vest date the Company’s shareholders approve an increase to the 2013 plan’s shares available for issuance by 220,266, the incentive awards shall automatically be modified to vest monthly over four years effective from their grant date.
The incentive award is a stock based compensation arrangement. As of December 31, 2013, the Company did not have sufficient shares available for issuance to settle the incentive awards in stock. Accordingly, settlement in cash is deemed more likely as of the balance sheet date. The Company accounted for these cash settled awards as a liability and will remeasure the awards at fair value at each reporting date until settled. Compensation expense and the related incentive award liability will be recognized over the vesting period of the incentive awards.
The Company recorded the fair value of the incentive awards using the Black-Scholes option pricing model using a stock price of $5, an exercise prices of $5, an expected term of 6 years, a volatility of 92%, and a dividend yield of 0% which resulted in a grant date fair value of $3.76 per share underlaying the incentive awards. The Company recorded $9,000 of compensation expense pertaining to incentive awards for the year ended December 31, 2013. The corresponding incentive award liability is presented in other liabilities in the accompanying balance sheet.
Restricted Stock Units
No restricted stock units were granted or were vested in the years ended December 31, 2013 and 2012. No restricted stock units were outstanding as of December 31, 2013. Nine restricted stock units were outstanding as of December 31 ,2012, and had a weighted-average grant date fair value of $238.50 per share and a weighted-average remaining contractual term of 0.64 years. No expense has been recorded to date related to the Company’s restricted stock units, as no restricted stock units have vested. Vesting of the restricted stock units was contingent upon either an initial public offering of the Company’s common stock or a change in control.
Stock-Based Compensation Expense
Employee and Director Expense
Employee and director stock-based compensation expense recorded was as follows (in thousands):


		Year Ended
		December 31
		2013				2012
Research and development		$	184			$	26
General and administrative			691				54

Total		$	875			$	80


In January 2004, the Company’s Board of Directors canceled outstanding employee options under the 1993 Stock Option Plan and replaced them with new options to purchase 1,230 shares of common stock under the 2003 Plan at an exercise price of $30.21 per share. These replacement options were fully vested on the grant date and are exercisable for ten years, or 18 months after an initial public offering, if earlier. All replacement options are being accounted for as variable from the date of issuance to the date the options are exercised, forfeited or expire. During the years ended December 31, 2013 and 2012, as a result of decreases in the fair market value of its common stock, the Company did not record any compensation expense related to these options.
Non-Employee Expense
The Company has issued options to purchase shares of common stock to members of its Scientific Advisory Board (SAB) and certain consultants. The stock options have various exercise prices, a term of ten years, and vest over periods up to sixty months. In 2013 and 2012, the Company granted to its SAB members and consultants options to purchase 6,833 and 3,145 shares of common stock, respectively. As of December 31, 2013, options to purchase 4,555 shares of common stock remained unvested, and compensation related to these stock options is subject to periodic adjustment as the shares vest. In 2013, the Company also issued an incentive award for 2,335 shares to an SAB member which remained unvested as of December 31, 2013. The Company recorded $17,000 and $6,000 of expense in the years ended December 31, 2013 and 2012, respectively, related to these options and awards.
The Company has not recognized, and does not expect to recognize in the near future, any tax benefit related to employee stock-based compensation costs.

401k_Plan

401(k) Plan	12 Months Ended
401(k) Plan	Dec. 31, 2013
Postemployment Benefits [Abstract]	'
401(k) Plan	'
	12. 401(k) Plan
	The Company provides a qualified 401(k) savings plan for its employees. All employees are eligible to participate, provided they meet the requirements of the plan. While the Company may elect to match employee contributions, no such matching contributions have been made through December 31, 2013 and 2012.

Income_Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	13. Income Taxes
	No provision for U.S. income taxes exists due to tax losses incurred in all periods presented. Deferred income taxes reflect the tax effects of net operating loss and tax credit carryforwards and the net temporary differences between the carrying amounts of assets and liabilities for financial reporting and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets are as follows (in thousands):


		December 31
		2013			2012
	Deferred tax assets:
	Federal and state net operating loss carryforwards	$	60,569		$	62,745
	Capitalized research and development		22,349			22,490
	Federal and state tax credit carryforwards		6,600			6,153
	Other		1,313			1,200

	Total deferred tax assets		90,831			92,588
	Valuation allowance		(90,831	)		(92,588	)

	Net deferred tax assets	$	—		$	—

	Realization of the net deferred tax assets is dependent upon future taxable income, if any, the amount and timing of which is uncertain. Based on the weight of available positive and negative objective evidence, management believes it more likely than not that the Company’s deferred tax assets are not realizable. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. The net valuation allowance decreased by $1.8 million during the year ended December 31, 2013 and increased $4.7 million during the year ended December 31, 2012.

	The following is a reconciliation of the expected statutory federal income tax provision to the actual income tax provision (in thousands):


		December 31
		2013			2012
	Expected income tax benefit at federal statutory tax rate	$	(3,424	)	$	(3,826	)
	Net operating loss reduction		4,441			—
	Change in valuation allowance		(1,757	)		4,668
	State income taxes, net of federal benefit		583			(763	)
	Permanent items		555			54
	Research credits		(396	)		—
	Other, net		(2	)		(133	)

	Income tax (benefit) expense	$	—		$	—

	Pursuant to Internal Revenue Code (“IRC”), Section 382 and 383, use of the Company’s U.S. federal and state net operating loss and research and development income tax credit carryforwards may be limited in the event of a cumulative change in ownership of more than 50.0% within a three-year period. The Company completed an analysis under IRC Sections 382 and 383 through December 21, 2007 and determined that the Company’s net operating losses and research and development credits were subject to limitations due to changes in ownership through December 31, 2007. The net operating loss carryforwards reflected in the deferred tax assets at December 31, 2013 have been adjusted to reflect Section 382 limitations resulting from the ownership change As the Company was in a net operating loss position for the year 2013 and 2012, the Company has not performed any additional analysis for IRC Sections 382 and 383 for the years ended December 31, 2013 and 2012. There is a risk that additional changes in ownership could have occurred since December 31, 2007. If a change in ownership were to have occurred, additional net operating loss and tax credit carryforwards could be eliminated or restricted. If eliminated, the related asset would be removed from the deferred tax asset schedule with a corresponding reduction in the valuation allowance.
	As of December 31, 2013, we had federal net operating loss carryforwards of $152.1 million and state net operating loss carryforwards of $152.2 million to offset future taxable income, if any. In addition, we had federal research and development tax credit carry forwards of $6.2 million and state research and development tax credit carryforwards of $3.2 million. If not utilized, the federal net operating loss and tax credit carryforwards will expire beginning in 2024 through 2033 and the state net operating loss carryforwards will expire beginning in 2014 through 2033. The state tax credit will carry forward indefinitely.

	The following table summarizes activity related to the Company’s gross unrecognized tax benefits (in thousands):


		Total
	Balance as of December 31, 2011	$	1,711
	Increases related to 2012 tax positions		36

	Balance as of December 31, 2012	$	1,747
	Increases related to prior year tax positions		65
	Increases related to 2013 tax positions		53

	Balance as of December 31, 2013	$	1,865

	The unrecognized tax benefits, if recognized, would not have an impact on the Company’s effective tax rate. The Company does not expect a significant change to its unrecognized tax benefits over the next twelve months. The unrecognized tax benefits may increase or change during the next year for items that arise in the ordinary course of business.
	The Company files income tax returns in the U.S. federal and California jurisdiction and is not currently under examination by federal, state, or local taxing authorities for any open tax years. The tax years 1998 through 2013 remain open to examination by the major taxing authorities.

RelatedParty_Transactions

Related-Party Transactions	12 Months Ended
Related-Party Transactions	Dec. 31, 2013
Related Party Transactions [Abstract]	'
Related-Party Transactions	'
	14. Related-Party Transactions
	The Company paid a former member of its Board of Directors, who is also a member of its Scientific and Clinical Advisory Boards, a total of $45,000 and $60,000 in the years ended December 31, 2013 and 2012, respectively, in monthly cash retainers. The Company also issued options to purchase shares of common stock and incentive awards to this individual in his capacity as a member of its Scientific Advisory Board (Note 11).

Subsequent_Events

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2013
Subsequent Events [Abstract]	'
Subsequent Events	'
	15. Subsequent Events
	Clinical Research and Development Agreement
	In February, 2014, the Company and INC Research entered into a master services agreement and related initial work order under the master services agreement to provide contract clinical research and development services to the Company. The master services agreement provides that the Company may engage INC Research from time to time to provide services in accordance with work orders mutually agreed and budgeted between the parties. The Company contemplates that the master services agreement will be utilized from time to time for clinical research and development of its product candidates and the initial work order includes services with respect to CymaBay’s lead clinical candidate, arhalofenate, which total is anticipated to exceed approximately $8 million. The master services agreement has a term of five years; however, the Company may terminate the master services agreement or any individual work order of the master services agreement on thirty (30) days written notice, or immediately in the event of any safety risk associated with the services being performed. In addition, either party may terminate the Agreement or any applicable work order upon thirty (30) days written notice for a material breach by the other party.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2013
Accounting Policies [Abstract]	'
Basis of Presentation and Use of Estimates	'
	Basis of Presentation and Use of Estimates
	The financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP), which requires management to make informed estimates and assumptions that impact the amounts and disclosures reported in the financial statements and accompanying notes. Management bases its estimates on historical experience and on assumptions believed to be reasonable under the circumstances. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Actual results could differ materially from those estimates. The Company believes significant judgment is involved in determining revenue recognition and in estimating stock-based compensation, clinical trial accruals, and equity instrument valuations.
Reverse Stock Split	'
	Reverse Stock Split
	On September 30, 2013, the Company filed amended and restated certificates of incorporation under which the Company’s preferred stock and common stock was reverse split on a 1-for-79.5 basis. The accompanying financial statements and notes to the financial statements, other than with respect to the authorized number of shares, give retroactive effect to the reverse split for all periods presented.
Reclassification of Prior Period Balances	'
	Reclassification of Prior Period Balances
	Certain reclassifications have been made to prior period amounts to conform to current-year presentation.
Fair Value of Financial Instruments	'
	Fair Value of Financial Instruments
	The Company’s financial instruments consist of cash and cash equivalents, short-term marketable securities, accounts payable, accrued expenses, warrant liabilities, forward contracts, and convertible notes. Fair value estimates of these instruments are made at a specific point in time, based on relevant market information. These estimates may be subjective in nature and involve uncertainties and matters of significant judgment and therefore cannot be determined with precision. The carrying amounts of cash and cash equivalents, accounts payable and accrued expenses are generally considered to be representative of their respective fair values because of the short-term nature of those instruments.
	Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. Assets and liabilities that are measured at fair value are reported using a three-level fair value hierarchy that prioritizes the inputs used to measure fair value. This hierarchy maximizes the use of observable inputs and maximizes the use of unobservable inputs and is as follows:
	Level 1—Quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.
	Level 2—Inputs other than quoted prices in active markets that are observable for the asset or liability, either directly or indirectly.
	Level 3—Inputs that are unobservable for the asset or liability.
	The following table presents the fair value of the Company’s financial assets and liabilities using the above input categories (in thousands):


		As of December 31, 2013
	Description	Level 1			Level 2			Level 3		Fair Value
	Money market funds	$	21,097		$	—		$	—	$	21,097
	Corporate debt and asset backed securities		—			6,843			—		6,843

	Total assets measured at fair value	$	21,097		$	6,843		$	—	$	27,940

	Forward contract	$	—		$	—		$	453	$	453
	Warrant liability		—			—			6,466		6,466

	Total liabilities measured at fair value	$	—		$	—		$	6,919	$	6,919

	Marketable securities consist of available-for-sale securities that are reported at fair value, with the related unrealized gains and losses included in accumulated other comprehensive income (loss), a component of stockholders’ equity (deficit). The Company values cash equivalents and marketable securities using quoted market prices or alternative pricing sources and models utilizing observable market inputs and, as such, classifies cash equivalents and marketable securities within Level 1 or Level 2.
	As of December 31, 2013, the Company held a Level 3 liability associated with warrants, issued in connection with the Company’s equity offerings, completed in September and October 2013. The warrants are considered liabilities and are valued using an option-pricing model, the significant unobservable inputs for which include exercise price of the warrants, market price of the underlying common shares, expected term, volatility based on a group of the Company’s peers and the risk-free rate corresponding to the expected term of the warrants. As of December 31, 2013, the Company also held a Level 3 liability associated with a forward contract which arose in connection with the Company’s November 22, 2013 execution of an equity purchase agreement with certain investors. The agreement required the Company to issue a fixed number of shares of common stock and warrants to purchase common stock at a predetermined price of $3.0 million provided the Company completes the listing of its common stock on a public stock exchange. The forward contract’s fair value was determined upon execution as the difference between the present value of the equity proceeds to be received under the agreement less the fair value of the underlying securities. The forward contract liability is presented in the balance sheet as a component of accrued liabilities and is revalued at each reporting period until the contract is settled which occurred on January 29, 2014. The fair value of the underlying common stock and warrants were valued using an option-pricing model, the inputs of which are similar to those used in the valuation of the Company’s liability classified warrants. Changes to any of the inputs to the option-pricing models used by the Company can have a significant impact to the estimated fair value of the warrants and forward contract liabilities. As of December 31, 2012, the Company had no assets or liabilities measured at fair value on a recurring basis within the Level 3 hierarchy.

	The following table sets forth a summary of the changes in the fair value of our Level 3 financial instruments (in thousands):


		Warrant			Forward
		Liability			Contract
	Balance as of December 31, 2012	$	—		$	—
	Issuance of financial instrument		5,972			453
	Change in fair value		494			—

	Balance as of December 31, 2013	$	6,466		$	453

	The gains and losses from remeasurement of Level 3 financial liabilities are recorded through other income, net on the accompanying statements of operations and comprehensive loss.
Cash, Cash Equivalents, and Marketable Securities	'
	Cash, Cash Equivalents, and Marketable Securities
	The Company considers all highly liquid investments with a remaining maturity of 90 days or less at the time of purchase to be cash equivalents. Cash and cash equivalents consist of deposits with commercial banks in checking, interest-bearing, and demand money market accounts. The Company invests excess cash in marketable securities with high credit ratings which are classified in Level 1 and Level 2 of the fair value hierarchy. These securities consist primarily of corporate debt and asset-backed securities and are classified as “available-for-sale.” Management may liquidate any of these investments in order to meet the Company’s liquidity needs in the next year. Accordingly, any investments with accompanying contractual maturities greater than one year from the balance sheet date are classified as short-term in the balance sheet.
	Realized gains and losses from the sale of marketable securities, if any, are calculated using the specific-identification method. Realized gains and losses and declines in value judged to be other-than- temporary are included in interest income or expense in the statements of operations and comprehensive loss. Unrealized holding gains and losses are reported in accumulated other comprehensive loss in the balance sheet. To date, the Company has not recorded any impairment charges on its marketable securities related to other-than-temporary declines in market value. In determining whether a decline in market value is other-than-temporary, various factors are considered, including the cause, duration of time and severity of the impairment, any adverse changes in the investees’ financial condition, and the Company’s intent and ability to hold the security for a period of time sufficient to allow for an anticipated recovery in market value.
Restricted Cash	'
	Restricted Cash
	The Company is required to maintain compensating cash balances with financial institutions that provide the Company with its corporate credit cards. As of December 31, 2013 and 2012, cash restricted under these arrangements was $155,000 and none, respectively. These amounts are presented in other assets on the accompanying balance sheets.
Concentration of Credit Risk	'
	Concentration of Credit Risk
	Cash, cash equivalents, and marketable securities consist of financial instruments that potentially subject the Company to a concentration of credit risk to the extent of the fair value recorded in the balance sheet. The Company invests cash that is not required for immediate operating needs primarily in highly liquid instruments that bear minimal risk. The Company has established guidelines relating to the quality, diversification, and maturities of securities to enable the Company to manage its credit risk.
Property and Equipment	'
	Property and Equipment
	Property and equipment is carried at cost, less accumulated depreciation and amortization. Depreciation and amortization is calculated using the straight-line method, and the cost is amortized over the estimated useful lives of the respective assets, generally three to seven years. Leasehold improvements are amortized over the shorter of the useful lives or the non-cancelable term of the related lease. Maintenance and repair costs are charged as expense in the statements of operations and comprehensive loss as incurred.
Impairment of Long-Lived Assets	'
	Impairment of Long-Lived Assets
	The Company reviews long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment loss is recognized if the estimated undiscounted future cash flow expected to result from the use and eventual disposition of an asset is less than the carrying amount. While the Company’s current and historical operating losses and cash flows are indicators of impairment, the Company believes the future cash flows to be received support the carrying value of its long-lived assets. Accordingly, the Company has not recognized any impairment losses as of December 31, 2013 and 2012.
Deferred Rent	'
	Deferred Rent
	The Company records its costs under facility operating lease agreements as rent expense. Rent expense is recognized on a straight-line basis over the non-cancelable term of the operating lease. The difference between the actual amounts paid and amounts recorded as rent expense is recorded to deferred rent in the accompanying balance sheets.
Revenue Recognition	'
	Revenue Recognition
	The Company recognizes revenue when (i) persuasive evidence of an arrangement exists, (ii) delivery has occurred or services have been rendered, (iii) the price is fixed and determinable, and (iv) collectability is reasonably assured. Payments received in advance of work performed are recorded as deferred revenue and recognized when earned. All revenue recognized to date under collaboration agreements has been nonrefundable.
	In 2012, contract revenue was from two strategic partners. There was no contract revenue recorded for the year ended December 31, 2013.
	Multiple Element Arrangements
	The Company evaluates revenue from agreements that have multiple elements to determine whether the components of the arrangement represent separate units of accounting. Management considers whether components of an arrangement represent separate units of accounting based upon whether certain criteria are met, including whether the delivered element has stand-alone value to the customer. To date, all of the Company’s collaboration agreements have been assessed to have one unit of accounting. Up-front and license fees received for a combined unit of accounting have been deferred and recognized ratably over the projected performance period. Non-refundable fees where the Company has no continuing performance obligations have been recognized as revenue when collection is reasonably assured and all other revenue recognition criteria have been met.
	Milestones and Contingent Payments
	Contingent consideration received from the achievement of a substantive milestone will be recognized in its entirety in the period in which the milestone is achieved. A milestone is defined as an event having all of the following characteristics: (i) there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved, (ii) the event can only be achieved based in whole or in part on either the company’s performance or a specific outcome resulting from the company’s performance and (iii) if achieved, the event would result in additional payments being due to the Company.
	The Company’s future research and development and license agreements may provide for success fees or payments to be paid to the Company upon the achievement of certain development milestones. Given the challenges inherent in developing biologic products, there may be substantial uncertainty as to whether any such milestones would be achieved at the time the agreements are executed. In addition, the Company will evaluate whether the development milestones meet all of the conditions to be considered substantive. The conditions include: (1) the consideration is commensurate with either of the following: (a) the Company’s performance to achieve the milestone or (b) the enhancement of the value of the delivered item or items as a result of a specific outcome resulting from the Company’s performance to achieve the milestone; (2) the consideration relates solely to past performance; and (3) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. If the Company considers the development milestones to be substantive, revenue related to such future milestone payments will be recognized as the Company achieves each milestone. Research and development funding internal and external research and development costs reimbursed in connection with research and development funding or collaboration agreements are recognized as revenue in the same period as the costs are incurred, and are presented on a gross basis because the Company acts as a principal, has the discretion to choose suppliers, bears credit risk, and performs part of the services.
Research and Development Expenses	'
	Research and Development Expenses
	Research and development expenses consist of costs incurred in identifying, developing, and testing product candidates. These expenses consist primarily of costs for research and development personnel, including related stock-based compensation; contract research organizations and other third parties that assist in managing, monitoring, and analyzing clinical trials; investigator and site fees; laboratory services; consultants; contract manufacturing services; non-clinical studies, including materials; and allocated expenses, such as depreciation of assets, and facilities and information technology that support research and development activities. Research and development costs are expensed as incurred, including expenses that may or may not be reimbursed under research and development funding arrangements. Research and development expenses under collaboration agreements approximate the revenue recognized under such agreements.

	The expenses related to clinical trials are based upon estimates of the services received and efforts expended pursuant to contracts with research institutions and clinical research organizations (CROs) that conduct and manage clinical trials on behalf of the Company. The Company’s objective is to reflect the appropriate trial expenses in its financial statements by matching those expenses with the period in which services and efforts are incurred. Expenses related to clinical trials are accrued based upon the level of activity incurred under each contract as indicated by such factors as progress made against specified milestones or targets in each period, patient enrollment levels, and other trial activities as reported by CROs. Accordingly, the Company’s clinical trial accrual is dependent upon the timely and accurate reporting of expenses by clinical research organizations and other third-party vendors. Payments made to third parties under these clinical trial arrangements in advance of the receipt of the related services are recorded as prepaid assets, depending on the terms of the agreement, until the services are rendered.
Stock-Based Compensation	'
	Stock-Based Compensation
	Employee and director stock-based compensation is measured at the grant date, based on the fair-value-based measurements of the stock awards, and the portion that is ultimately expected to vest is recognized as an expense over the related vesting periods, net of estimated forfeitures. The Company calculates the fair-value-based measurements of options using the Black-Scholes valuation model and recognizes expense using the straight-line attribution method.
	Equity awards granted to non-employees are accounted for using the Black-Scholes valuation model to determine the fair value-based measurements of such instruments. The fair value-based measurements of options and warrants granted to non-employees are re-measured over the related vesting period and amortized to expense as earned.
Common Stock Warrants	'
	Common Stock Warrants
	The Company’s outstanding common stock warrants issued in with the 2013 financing are classified as liabilities in the accompanying balance sheets as they contain provisions that could require the Company to settle the warrants in cash. The warrants were recorded at fair value using either the Black-Scholes option pricing model, probability weighted expected return model or a binomial model, depending on the characteristics of the warrants. The fair value of these warrants is re-measured at each financial reporting period with any changes in fair value being recognized as a component of other income (expense) in the accompanying statements of operations and comprehensive loss.
Income Taxes	'
	Income Taxes
	The Company utilizes the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on differences between the financial reporting and the tax bases of assets and liabilities and are measured using enacted tax rates and laws that will be in effect when the differences are expected to reverse. A valuation allowance is recorded when it is more likely than not that all or part of a deferred tax asset will not be realized.
	The accounting guidance for uncertainty in income taxes prescribes a recognition threshold and measurement attribute criteria for the financial recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination based on the technical merits of the position.
	The Company records interest related to income taxes, if any, as interest, and any penalties would be recorded as other expense in the statements of operations and comprehensive loss. There was no interest or penalties related to income taxes recorded during the years ended December 31, 2013 and 2012.
Comprehensive Loss	'
	Comprehensive Loss
	Comprehensive loss includes net loss and net unrealized gains and losses on marketable securities, which are presented in a single continuous statement. Comprehensive loss is disclosed in the statements of convertible preferred stock and stockholders’ deficit, and is stated net of related tax effects, if any.
Net Income (Loss) Per Common Share	'
	Net Income (Loss) Per Common Share
	Basic net income (loss) per share of common stock is based on the weighted average number of shares of common stock outstanding equivalents during the period. Prior to the 2013 financing, in addition to common stock, the Company had redeemable convertible preferred stock outstanding that contractually entitled the holder to participate in dividends and earnings of the Company. Accordingly, the Company applied the two-class method for calculating net income (loss) per share. Under this method, all undistributed earnings were allocated first to the preferred stockholders based on their contractual right to dividends. This right was calculated on a pro rated basis for the portion of the period the preferred shares were outstanding. In addition, in connection with the 2013 financing, during the year ended December 31, 2013, the Company converted all outstanding redeemable convertible preferred stock into common stock. The excess of the carrying amount of such redeemable convertible preferred stock over the fair value of the consideration paid to the holders was treated as an adjustment that reduced preferred stockholders’ dividend or distribution entitlement. The amount of earnings that resulted from adjusting net loss for the period as described above was allocated between weighted average number of participating preferred and common stock shares based on their entitlement to such distributions as if all of the earnings of the period had been distributed.
	Diluted net loss per share of common stock is calculated using the more dilutive of the two approaches: one, “as-converted” method, under which the weighted average number of common stock shares outstanding during the period is adjusted to include the assumed conversion of redeemable convertible preferred stock at the beginning of the period, and the other, the “two-class” method as described above. Under either approach, the weighted average number of shares outstanding is also adjusted to include the assumed exercises of stock options and warrants, if dilutive. For periods in which the Company has basic net loss per share of common stock, such as for the years ended December 31, 2013 and 2012, diluted net loss per share is the same as basic, as any adjustments would have been anti-dilutive. For the year ending December 31, 2013, the Company’s diluted net loss per common share was calculated using the “as-converted” method, as it resulted in a net loss per share of common stock and accordingly, was more dilutive than the “two-class” method.
	In all periods presented, the Company’s outstanding stock options and warrants were excluded from the calculation of earnings (loss) per share because the effect would be antidilutive.
	The following table sets forth the computation of basic and diluted net income (loss) per share (in thousands, except share and per share amounts):


		Year Ended December 31,
		2013			2012
	Basic:
	Numerator:
	Net loss	$	(10,073	)	$	(11,255	)
	Accretion to redemption value of redeemable convertible preferred stock		(9,289	)		(12,644	)
	Reduction in redeemable convertible preferred stock distribution entitlement upon extinguishment		313,933			—
	Amounts allocated to participating redeemable convertible preferred stock		(50,577	)		—

	Net income (loss) allocated to common stock—basic	$	243,994		$	(23,899	)

	Denominator:
	Weighted average number of common stock shares outstanding		2,357,036			5,788

	Net income (loss) per share—basic:	$	103.52		$	(4,128.71	)
	Diluted:
	Numerator:
	Net income (loss) allocated to common stock	$	243,994		$	(23,899	)
	Adjustments from assumed conversion of redeemable convertible preferred stock		(254,067	)		—

	Net loss allocated to common stock—diluted	$	(10,073	)	$	(23,899	)

	Denominator:
	Weighted average number of common stock shares outstanding		2,357,036			5,788
	Weighted average number of preferred stock shares outstanding		488,573			—

	Total common stock shares equivalents		2,845,609			5,788

	Net loss per share—diluted:	$	(3.54	)	$	(4,128.71	)
	The following table shows the total outstanding securities considered anti-dilutive and therefore excluded from the computation of diluted net income (loss) per share (in thousands):


		Year ended
		December 31,
		2013			2012
	Warrants for common stock		1,743			28
	Common stock options		577			104
	Redeemable convertible preferred stock		—			661

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
Summary of Significant Accounting Policies (Tables)	Dec. 31, 2013
Accounting Policies [Abstract]	'
Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis	'
	The following table presents the fair value of the Company’s financial assets and liabilities using the above input categories (in thousands):


		As of December 31, 2013
	Description	Level 1			Level 2			Level 3		Fair Value
	Money market funds	$	21,097		$	—		$	—	$	21,097
	Corporate debt and asset backed securities		—			6,843			—		6,843

	Total assets measured at fair value	$	21,097		$	6,843		$	—	$	27,940

	Forward contract	$	—		$	—		$	453	$	453
	Warrant liability		—			—			6,466		6,466

	Total liabilities measured at fair value	$	—		$	—		$	6,919	$	6,919

Schedule of Changes in Fair Value of Financial Instruments	'
	The following table sets forth a summary of the changes in the fair value of our Level 3 financial instruments (in thousands):


		Warrant			Forward
		Liability			Contract
	Balance as of December 31, 2012	$	—		$	—
	Issuance of financial instrument		5,972			453
	Change in fair value		494			—

	Balance as of December 31, 2013	$	6,466		$	453

Schedule of Basic and Diluted Net Income (Loss) per Share	'
	The following table sets forth the computation of basic and diluted net income (loss) per share (in thousands, except share and per share amounts):


		Year Ended December 31,
		2013			2012
	Basic:
	Numerator:
	Net loss	$	(10,073	)	$	(11,255	)
	Accretion to redemption value of redeemable convertible preferred stock		(9,289	)		(12,644	)
	Reduction in redeemable convertible preferred stock distribution entitlement upon extinguishment		313,933			—
	Amounts allocated to participating redeemable convertible preferred stock		(50,577	)		—

	Net income (loss) allocated to common stock—basic	$	243,994		$	(23,899	)

	Denominator:
	Weighted average number of common stock shares outstanding		2,357,036			5,788

	Net income (loss) per share—basic:	$	103.52		$	(4,128.71	)
	Diluted:
	Numerator:
	Net income (loss) allocated to common stock	$	243,994		$	(23,899	)
	Adjustments from assumed conversion of redeemable convertible preferred stock		(254,067	)		—

	Net loss allocated to common stock—diluted	$	(10,073	)	$	(23,899	)

	Denominator:
	Weighted average number of common stock shares outstanding		2,357,036			5,788
	Weighted average number of preferred stock shares outstanding		488,573			—

	Total common stock shares equivalents		2,845,609			5,788

	Net loss per share—diluted:	$	(3.54	)	$	(4,128.71	)
Anti Dilutive Securities Excluded From the Computation of Diluted Net Loss Per Share	'
	The following table shows the total outstanding securities considered anti-dilutive and therefore excluded from the computation of diluted net income (loss) per share (in thousands):


		Year ended
		December 31,
		2013			2012
	Warrants for common stock		1,743			28
	Common stock options		577			104
	Redeemable convertible preferred stock		—			661

Marketable_Securities_Tables

Marketable Securities (Tables)	12 Months Ended
Marketable Securities (Tables)	Dec. 31, 2013
Cash And Cash Equivalents [Abstract]	'
Marketable Available-for-Sale Securities	'
	Marketable available-for-sale securities as of December 31, 2013 consist of the following (in thousands):


		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair Value
				Gains		Losses
	As of December 31, 2013:
	Corporate debt securities	$	6,355	$	3	$	(2	)	$	6,356
	Asset-backed securities		486		1		—			487

		$	6,841	$	4	$	(2	)	$	6,843

Certain_Balance_Sheet_Items_Ta

Certain Balance Sheet Items (Tables)	12 Months Ended
Certain Balance Sheet Items (Tables)	Dec. 31, 2013
Organization Consolidation And Presentation Of Financial Statements [Abstract]	'
Property and Equipment	'
	Property and equipment consists of the following (in thousands):


		December 31,
		2013			2012
	Laboratory equipment	$	—		$	3,778
	Office and computer equipment		556			983
	Purchased software		166			166
	Furniture and fixtures		42			174
	Leasehold improvements		2,534			2,534

	Total		3,298			7,635
	Less accumulated depreciation and amortization		(3,295	)		(7,551	)

	Property and equipment, net	$	3		$	84

Accrued Liabilities	'
	Accrued liabilities consist of the following (in thousands):


		December 31,
		2013			2012
	Accrued compensation	$	518		$	291
	Accrued pre-clinical and clinical trial expenses		418			304
	Accrued professional fees		782			285
	Forward contract		453			—
	Other accruals		80			110

	Total accrued liabilities	$	2,251		$	990

Debt_Tables

Debt (Tables)	12 Months Ended
Debt (Tables)	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Schedule of Future Principal Payments Due under Loan Facility	'
	Future principal payments due under the loan facility are as follows (in thousands):


		Principal
		Payments
	Year ending December 31:
	2014	$	245
	2015		1,546
	2016		1,687
	2017		1,522

	Total future principal payments due under loan agreement	$	5,000

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
Commitments and Contingencies (Tables)	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Future Minimum Lease Payments	'
	Future minimum lease payments under operating lease commitments are as follows (in thousands):


		Lease
		Payments
	Year ending December 31:
	2014	$	337
	2015		209
	2016		216
	2017		222
	2018		228

	Total future minimum payments	$	1,212

Redeemable_Convertible_Preferr1

Redeemable Convertible Preferred Stock (Tables)	12 Months Ended
Redeemable Convertible Preferred Stock (Tables)	Dec. 31, 2013
Equity [Abstract]	'
Summary of Convertible Preferred Stock	'
	As of December 31, 2012, convertible preferred stock balances were as follows (in thousands, except share amounts):


		Shares		Shares		Aggregate		Carrying
		Authorized		Issued and		Liquidation		Value
				Outstanding		Preference
	Series A-1		12,734		12,734	$	5,187	$	75,454
	Series B-1		373,223		373,223		146,549		145,408
	Series C-1		75,472		27,345		15,122		15,074
	Series D-1		136,948		136,949		46,520		43,271
	Series E-1		40,252		39,265		19,820		10,674
	Series E-3		93,082		71,543		23,552		28,816

	Total		731,711		661,059	$	256,750	$	318,697

Common_Stock_Tables

Common Stock (Tables)	12 Months Ended
Common Stock (Tables)	Dec. 31, 2013
Equity [Abstract]	'
Reserved Shares of Authorized but Unissued Common Stock	'
	As of December 31, 2013 and December 31, 2012, the Company had reserved shares of authorized but unissued common stock as follows:


		Shares Reserved		Shares Reserved
		December 31, 2013		December 31, 2012
	Outstanding common stock warrants		1,742,727		28,208
	Equity incentive plans		577,294		140,474
	Convertible preferred stock		—		661,059

	Total reserved shares of common stock		2,320,021		829,741

Stock_Plans_and_StockBased_Com1

Stock Plans and Stock-Based Compensation (Tables)	12 Months Ended
Stock Plans and Stock-Based Compensation (Tables)	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Summary of Stock Option Activity	'
	The following table summarizes stock option activity:


		Shares			Weighted-			Weighted-		Aggregate
		Subject to			Average			Average		Intrinsic
		Outstanding			Exercise			Remaining		Value (in
		Options			Price of			Contractual		thousands)
					Options			Term
								(Years)
	Outstanding as of December 31, 2012		103,760		$	34.19			4.43	$	—
	Options granted		487,697			5
	Options exercised		(77	)		4.77
	Options forfeited		(3,490	)		10.36
	Options expired		(10,637	)		31.31

	Outstanding as of December 31, 2013		577,253		$	7			9.57	$	3

	Vested and expected to vest as of December 31, 2013		557,995		$	7.07			9.56	$	3

	Exercisable as of December 31, 2013		289,308		$	9.55			9.25	$	1
Summary of Stock Options Outstanding	'
	The following table summarizes information about stock options outstanding as of December 31, 2013 :


		Options Outstanding						Options Exercisable
	Exercise Price	Number			Weighted-			Number of Shares
		of			Average
		Shares			Remaining
					Contractual
					Term
					(Years)
	$4.77		12,257			7.62			8,815
	$5.00		548,544			9.88			264,041
	$15.90		839			0.27			839
	$30.21		8,638			0.41			8,638
	$39.75		3,520			0.27			3,520
	$238.50		3,455			2.73			3,455

			577,253			9.57			289,308

Estimated Weighted-Average Grant Date Fair Value	'
	The following table presents the weighted-average assumptions the Company used with the Black-Scholes valuation model to derive the grant date fair value-based measurements of employee and director stock options and the resulting estimated weighted-average grant date fair-value-based measurements per share:


		Year Ended December 31,
		2013			2012
	Weighted-average assumptions:
	Expected term		6 yrs			6.25 yrs
	Expected volatility		92	%		100	%
	Risk-free interest rate		1.76	%		1.01	%
	Expected dividend yield		0	%		0	%
	Weighted-average grant date fair value per share	$	3.76		$	3.97
Summary of Stock-Based Compensation Expense	'
	Employee and director stock-based compensation expense recorded was as follows (in thousands):


		Year Ended
		December 31
		2013			2012
	Research and development	$	184		$	26
	General and administrative		691			54

	Total	$	875		$	80

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Components of Deferred Tax Assets	'
	Significant components of the Company’s deferred tax assets are as follows (in thousands):


		December 31
		2013			2012
	Deferred tax assets:
	Federal and state net operating loss carryforwards	$	60,569		$	62,745
	Capitalized research and development		22,349			22,490
	Federal and state tax credit carryforwards		6,600			6,153
	Other		1,313			1,200

	Total deferred tax assets		90,831			92,588
	Valuation allowance		(90,831	)		(92,588	)

	Net deferred tax assets	$	—		$	—

Summary of Reconciliation of Expected Statutory Federal Income Tax Provision to Actual Income Tax Provision	'
	The following is a reconciliation of the expected statutory federal income tax provision to the actual income tax provision (in thousands):


		December 31
		2013			2012
	Expected income tax benefit at federal statutory tax rate	$	(3,424	)	$	(3,826	)
	Net operating loss reduction		4,441			—
	Change in valuation allowance		(1,757	)		4,668
	State income taxes, net of federal benefit		583			(763	)
	Permanent items		555			54
	Research credits		(396	)		—
	Other, net		(2	)		(133	)

	Income tax (benefit) expense	$	—		$	—

Summary of Gross Unrecognized Tax Benefits	'
	The following table summarizes activity related to the Company’s gross unrecognized tax benefits (in thousands):


		Total
	Balance as of December 31, 2011	$	1,711
	Increases related to 2012 tax positions		36

	Balance as of December 31, 2012	$	1,747
	Increases related to prior year tax positions		65
	Increases related to 2013 tax positions		53

	Balance as of December 31, 2013	$	1,865

Organization_and_Description_o1

Organization and Description of Business - Additional Information (Detail) (USD $)	0 Months Ended			12 Months Ended
	Nov. 22, 2013	Oct. 31, 2013	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jun. 20, 2006
Organization Consolidation And Presentation Of Financial Statements [Abstract]	'	'	'	'	'	'	'
Accumulated deficit	'	'	'	($348,842,000)	($329,480,000)	'	'
Net losses	'	'	'	-10,073,000	-11,255,000	'	'
Cash flows from operating activities	'	'	'	-8,458,000	-11,293,000	'	'
Product sales	'	'	'	0	'	'	'
Gross proceeds from issuance of common stock and warrants in a private placement	2,700,000	'	26,800,000	'	'	'	'
Additional proceeds from venture debt financing	'	'	5,000,000	'	'	'	'
Venture debt financing loan agreement amount	'	'	10,000,000	'	'	'	30,000,000
Net proceeds after deducting placement agent fees and estimated offering expenses	'	'	28,800,000	'	'	'	'
Issued shares of common stock in cancellation of debt	'	'	16,900,000	'	'	'	'
Net proceeds from issuance of private placement	'	2,200,000	22,800,000	'	'	'	'
Cash and cash equivalents	'	'	'	24,401,000	7,726,000	8,021,000	'
Marketable securities	'	'	'	$6,843,000	'	'	'

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012
Product Information [Line Items]	'	'	'
Reverse stock split	0.01258	'	'
Assets measured at fair value on a recurring basis within Level 3	'	'	$0
Liabilities measured at fair value on a recurring basis within Level 3	'	'	0
Predetermined price of common stock purchased for warrants	'	'	3,000,000
Restricted cash	'	155,000	0
Impairment losses	'	0	0
Contract revenue	'	0	3,050,000
Income tax interest & penalties	'	$0	$0
Minimum [Member]	'	'	'
Product Information [Line Items]	'	'	'
Property and equipment, estimated useful lives	'	'3 years	'
Maximum [Member]	'	'	'
Product Information [Line Items]	'	'	'
Property and equipment, estimated useful lives	'	'7 years	'

Summary_of_Significant_Account4

Summary of Significant Accounting Policies - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2013
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'
Total assets measured at fair value	$27,940
Total liabilities measured at fair value	6,919
Forward contract [Member]	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'
Total liabilities measured at fair value	453
Warrant liability [Member]	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'
Total liabilities measured at fair value	6,466
Money market funds [Member]	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'
Total assets measured at fair value	21,097
Corporate debt and asset backed securities [Member]	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'
Total assets measured at fair value	6,843
Level 1 [Member]	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'
Total assets measured at fair value	21,097
Level 1 [Member] \| Money market funds [Member]	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'
Total assets measured at fair value	21,097
Level 2 [Member]	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'
Total assets measured at fair value	6,843
Level 2 [Member] \| Corporate debt and asset backed securities [Member]	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'
Total assets measured at fair value	6,843
Level 3 [Member]	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'
Total liabilities measured at fair value	6,919
Level 3 [Member] \| Forward contract [Member]	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'
Total liabilities measured at fair value	453
Level 3 [Member] \| Warrant liability [Member]	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'
Total liabilities measured at fair value	$6,466

Summary_of_Significant_Account5

Summary of Significant Accounting Policies - Schedule of Changes in Fair Value of Warrant Liability (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Schedule Of Changes In Fair Value Of Warrant Liability [Line Items]	'
Balance as of December 31, 2013	$6,919
Level 3 [Member]	'
Schedule Of Changes In Fair Value Of Warrant Liability [Line Items]	'
Balance as of December 31, 2013	6,919
Level 3 [Member] \| Warrant liability [Member]	'
Schedule Of Changes In Fair Value Of Warrant Liability [Line Items]	'
Issuance of financial instrument	5,972
Change in fair value	494
Balance as of December 31, 2013	6,466
Level 3 [Member] \| Forward contract [Member]	'
Schedule Of Changes In Fair Value Of Warrant Liability [Line Items]	'
Issuance of financial instrument	453
Balance as of December 31, 2013	$453

Summary_of_Significant_Account6

Summary of Significant Accounting Policies - Schedule of Basic and Diluted Net Income (Loss) per Share (Detail) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Basic:	'	'
Net loss	($10,073)	($11,255)
Accretion to redemption value of redeemable convertible preferred stock	-9,289	-12,644
Reduction in redeemable convertible preferred stock distribution entitlement upon extinguishment	313,933	'
Amounts allocated to participating redeemable convertible preferred stock	-50,577	'
Net income (loss) allocated to common stockholders	243,994	-23,899
Weighted average number of common stock shares outstanding	2,357,036	5,788
Net income (loss) per share-basic:	$103.52	($4,128.71)
Diluted:	'	'
Net income (loss) allocated to common stockholders	243,994	-23,899
Adjustments from assumed conversion of redeemable convertible preferred Stock	-254,067	'
Net loss allocated to common stock-diluted	($10,073)	($23,899)
Total common stock shares equivalents	2,845,609	5,788
Net loss per share-diluted:	($3.54)	($4,128.71)
Common Stock [Member]	'	'
Diluted:	'	'
Total common stock shares equivalents	2,357,036	5,788
Preferred Stock [Member]	'	'
Diluted:	'	'
Total common stock shares equivalents	488,573	'

Summary_of_Significant_Account7

Summary of Significant Accounting Policies - Anti Dilutive Securities Excluded From Computation of Diluted Net Loss Per Share (Detail)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Redeemable Convertible Preferred Stock [Member]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Anti-dilutive securities excluded from the computation of diluted loss per share	'	661
Common Stock [Member]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Anti-dilutive securities excluded from the computation of diluted loss per share	577	104
Warrants for common stock [Member]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Anti-dilutive securities excluded from the computation of diluted loss per share	1,743	28

Marketable_Securities_Marketab

Marketable Securities - Marketable Available-for-Sale Securities (Detail) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'
Amortized Cost	$6,841
Gross Unrealized Gains	4
Gross Unrealized Losses	-2
Estimated Fair Value	6,843
Corporate debt securities [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Amortized Cost	6,355
Gross Unrealized Gains	3
Gross Unrealized Losses	-2
Estimated Fair Value	6,356
Asset-backed securities [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Amortized Cost	486
Gross Unrealized Gains	1
Gross Unrealized Losses	'
Estimated Fair Value	$487

Marketable_Securities_Addition

Marketable Securities - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]	'	'
Marketable Securities	'	$0
Marketable investments continuous unrealized loss position	$0	'
Corporate debt securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Marketable securities contractual maturities	'Less than one year	'
Asset-backed securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Marketable securities contractual maturities	'Between 2-5 years	'

Certain_Balance_Sheet_Items_Pr

Certain Balance Sheet Items - Property Plant and Equipment (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	$3,298	$7,635
Less accumulated depreciation and amortization	-3,295	-7,551
Property and equipment, net	3	84
Laboratory equipment [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	'	3,778
Office and Computer equipment [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	556	983
Purchased software [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	166	166
Furniture and fixtures [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	42	174
Leasehold improvements [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, gross	$2,534	$2,534

Certain_Balance_Sheet_Items_Ac

Certain Balance Sheet Items - Accrued Liabilities (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]	'	'
Accrued compensation	$518	$291
Accrued pre-clinical and clinical trial expenses	418	304
Accrued professional fees	782	285
Forward contract	453	'
Other accruals	80	110
Total accrued liabilities	$2,251	$990

Collaboration_Agreements_Addit

Collaboration Agreements - Additional Information (Detail) (USD $)

12 Months Ended

0 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Jul. 21, 2010

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Mar. 31, 2010

Dec. 31, 2013

Mar. 31, 2010

Dec. 31, 2012

Sanofi-Aventis [Member]

Pfizer, Inc. [Member]

Takeda Pharmaceutical Company Limited [Member]

Up-front license payment [Member]

Technology access fee [Member]

Research and development funding [Member]

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

Payments received

$25,000,000

Contract revenue

3,050,000

2,900,000

100,000

Deferred revenue, payment received

$1,500,000

$900,000

$600,000

License_Agreements_Additional_

License Agreements - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 1998
Business Combinations [Abstract]	'	'	'
Monthly license fees	'	'	$2,000
Potential future development payments	'	'	800,000
Development payment	0	0	'
Royalty payment	$0	$0	'

Debt_Additional_Information_De

Debt - Additional Information (Detail) (USD $)

0 Months Ended

9 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

9 Months Ended

1 Months Ended

Sep. 30, 2013

Dec. 31, 2013

Dec. 31, 2012

Jun. 20, 2006

Dec. 31, 2013

Sep. 30, 2013

Dec. 31, 2010

Jul. 31, 2009

Feb. 28, 2009

Jan. 31, 2012

Mar. 31, 2008

Sep. 30, 2008

Dec. 31, 2013

Sep. 30, 2013

Feb. 28, 2009

Jul. 31, 2013

Mar. 31, 2013

Jan. 31, 2012

Jul. 31, 2009

Jul. 31, 2013

Mar. 31, 2013

Jan. 31, 2012

Warrants, Exercise price of $5.00 per share [Member]

Series E-1 Preferred [Member]

Series C-1 Preferred [Member]

First Issuance [Member]

Second Issuance [Member]

Facility Loan Agreement [Member]

Third Issuance [Member]

Fourth Issuance [Member]

As Amended [Member]

First Tranche [Member]

Second Tranche [Member]

Scenario one, conversion basis [Member]

Wall Street Journal Prime Rate [Member]

As Amended [Member]

Second Tranche [Member]

Scenario two [Member]

Second Tranche [Member]

Debt Instrument [Line Items]

Maximum borrowing capacity

$10,000,000

$30,000,000

$10,000,000

Notes issued

3,500,000

10,500,000

7,000,000

6,700,000

Maturity date of debt

17-Mar-11

17-Sep-11

28-Feb-12

31-Dec-13

1-Aug-13

1-Mar-13

31-Jul-12

31-Dec-13

1-Aug-13

1-Mar-13

Facility loan, fixed interest rate

7.57%

8.75%

4.42%

4.92%

4.96%

5.46%

Conversion price

$232.93

$438.84

$292.56

Interest expense

600,000

700,000

Loan facility, outstanding principal and accrued interest settled

16,900,000

Loan facility extinguished in exchange of common stock

624,944

Facility loan, drawn

4,853,000

5,000,000

Facility loan, fixed interest rate

8.75%

Facility loan, prime rate plus

4.25%

Facility loan, interest amortization period

'36 months

Percentage of principal amount as final payment

6.50%

Facility loan, financial covenants

'Company must maintain compliance with one of two financial covenants at all times (1) maintain 1.3 times cash to outstanding debt or (2) maintain sufficient cash on hand to support eight months of operations based on a trailing average monthly cash burn.

Aggregate outstanding term loans percentage

100.00%

Prepayment fee percentage

3.00%

Facility fee

1.00%

Warrants issued

121,739

Exercise price

Long term warrant liability

$500,000

Debt_Schedule_of_Future_Princi

Debt - Schedule of Future Principal Payments Due under Loan Facility (Detail) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2013
Maturities Of Long Term Debt [Abstract]	'
2014	$245
2015	1,546
2016	1,687
2017	1,522
Total future principal payments due under loan agreement	$5,000

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended		0 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Nov. 08, 2013
			New Lease Agreement [Member]
			sqft
Loss Contingencies [Line Items]	'	'	'
Lease start date	'	'	16-Jan-14
Lease expiration date	30-Apr-14	'	31-Dec-18
Area of office space	'	'	8,894
Rent expenses	$0.50	$0.50	'
Operating leases term	'	'4 years	'
Accrued in the balance sheets related to indemnification obligations	'	'	'
Indemnification liabilities	$0	$0	'

Commitments_and_Contingencies_2

Commitments and Contingencies - Future Minimum Lease Payments (Detail) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]	'
2014	$337
2015	209
2016	216
2017	222
2018	228
Total future minimum payments	$1,212

Redeemable_Convertible_Preferr2

Redeemable Convertible Preferred Stock - Additional Information (Detail) (USD $)

0 Months Ended

1 Months Ended

9 Months Ended

12 Months Ended

1 Months Ended

9 Months Ended

12 Months Ended

1 Months Ended

2 Months Ended

4 Months Ended

9 Months Ended

12 Months Ended

1 Months Ended

9 Months Ended

12 Months Ended

1 Months Ended

9 Months Ended

12 Months Ended

1 Months Ended

9 Months Ended

12 Months Ended

1 Months Ended

9 Months Ended

12 Months Ended

Sep. 30, 2013

Aug. 31, 2008

Sep. 30, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2010

Dec. 31, 2013

Aug. 31, 2008

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2012

Nov. 30, 2009

Aug. 31, 2008

Dec. 31, 2004

Dec. 31, 2003

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2012

Aug. 31, 2006

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2012

Aug. 31, 2008

Apr. 30, 2007

Sep. 30, 2013

Dec. 31, 2012

Dec. 31, 2010

Sep. 30, 2012

Dec. 30, 2010

Jun. 30, 2010

Nov. 30, 2009

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2012

Aug. 31, 2008

Sep. 30, 2013

Dec. 31, 2012

Dec. 31, 2010

Sep. 30, 2012

Dec. 31, 2013

Next sale and issuance of capital stock of the Company [Member]

Scenario two [Member]

Series A-1 Preferred [Member]

Series B-1 Preferred [Member]

Series C-1 Preferred [Member]

Series D-1 Preferred [Member]

Series E-1 Preferred [Member]

Warrants for common stock [Member]

Series E-3 Convertible Preferred Stock [Member]

Series B-1 Preferred Stock [Member]

Series D-1 and E Preferred Stock [Member]

Minimum [Member]

Next sale and issuance of capital stock of the Company [Member]

Scenario one, conversion basis [Member]

Minimum [Member]

Maximum [Member]

Temporary Equity [Line Items]

Issuance of common stock upon conversion of redeemable convertible preferred stock

2,793,281

Conversion of preferred stock to common stock

$323,155,000

Convertible preferred stock issued

661,059

12,734

188,894

136,520

373,223

27,345

137,592

136,949

39,265

71,543

Convertible preferred stock outstanding

661,059

12,734

373,223

27,345

136,949

39,265

71,543

Purchase price per share of preferred stock

$232.93

$365.70

$232.94

$232.93

Preferred stock balances, price per share

$18.64

$29.26

$18.64

Proceed from issuance of redeemable preferred stock

44,000,000

31,800,000

10,000,000

32,000,000

Warrant to purchase common stock, issued

29,245

20,639

Warrant issued, exercise price per share

30.21

22.13

Common stock, price per share

$1.51

$0.79

warrant issued, exercise period

'5 years

Warrant, extended expiration date

31-Dec-11

1-Apr-13

13-Apr-13

Percentage of reduction in number of shares exercisable

45.00%

Number of warrants outstanding

14,623

13,160

Repurchase of Stock, shares

646

1,610

472

Repurchase of Stock, value

82,000

-8,247,000

Shares issued upon conversion of debt

2,793,281

37,119

859

1,288

71,543

Aggregate cumulative dividend

2,300,000

2,200,000

63,100,000

59,600,000

5,600,000

5,100,000

15,900,000

14,600,000

1,900,000

1,500,000

3,400,000

2,700,000

Aggregate cumulative dividend, per share

$183.64

$174.40

$168.96

$159.72

$201.83

$187.32

$116

$106.75

$48.14

$38.90

$47.28

$38.04

Preferred stock liquidation preference

$232.93

$365.70

$232.93

$290.97

$465.87

Conversion basis, Percentage of outstanding common stock

66.67%

51.00%

Per share price

Aggregate gross proceed

$30,000,000

Participation percentage in financing

1.00%

99.00%

Conversion ratio

0.25

Participation right, description

'Any holder that participated in the 2013 financing for between 100% and 300% of such holder's Pro Rata Share (the "Participation Multiple") had each share of preferred stock convert into shares of common stock by multiplying the product of (y) the aggregate number of shares of preferred stock held by such holder multiplied by the applicable Participation Multiple and (z) four (4).

Redeemable_Convertible_Preferr3

Redeemable Convertible Preferred Stock - Summary of Convertible Preferred Stock (Detail) (USD $)

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2004

Dec. 31, 2003

Dec. 31, 2012

Aug. 31, 2006

Dec. 31, 2012

Apr. 30, 2007

Dec. 31, 2012

In Thousands, except Share data, unless otherwise specified

Scenario, Previously Reported [Member]

Series A-1 Preferred [Member]

Series B-1 Preferred [Member]

Series C-1 Preferred [Member]

Series D-1 Preferred [Member]

Series E-1 Preferred [Member]

Series E-3 Convertible Preferred Stock [Member]

Class of Stock [Line Items]

Shares Authorized

55,258,608

731,711

12,734

373,223

75,472

136,948

40,252

93,082

Shares Issued

661,059

12,734

373,223

188,894

136,520

27,345

136,949

137,592

39,265

71,543

Shares Outstanding

661,059

12,734

373,223

27,345

136,949

39,265

71,543

Aggregate Liquidation Preference

$256,750

$5,187

$146,549

$15,122

$46,520

$19,820

$23,552

Carrying Value

$318,697

$75,454

$145,408

$15,074

$43,271

$10,674

$28,816

Common_Stock_Additional_Inform

Common Stock - Additional Information (Detail) (USD $)

0 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

Nov. 22, 2013

Oct. 31, 2013

Sep. 30, 2013

Dec. 31, 2013

Dec. 31, 2010

Dec. 31, 2012

Dec. 31, 2013

Sep. 30, 2013

Nov. 30, 2009

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2004

Dec. 31, 2012

Dec. 31, 2010

Apr. 30, 2007

Dec. 31, 2010

Warrants, Exercise price of $5.75 per share [Member]

Warrants, Exercise price of $5.00 per share [Member]

Series B-1 Preferred [Member]

Series D-1 Preferred [Member]

Scenario, Previously Reported [Member]

Warrants for common stock [Member]

Minimum [Member]

Maximum [Member]

Class of Stock [Line Items]

Common stock, shares authorized

100,000,000

74,000,000

100,000,000

Number of common stock shares issued upon conversion redeemable convertible preferred stock

2,793,281

Carrying value of common stock upon conversion of redeemable convertible preferred stock

$320,000,000

$319,736,000

Common stock shares sold

604,000

664,300

5,366,669

9,455,064

5,792

Warrants to purchase shares of common stock in private placement

120,800

132,860

1,073,338

Net proceeds from issuance of private placement

2,200,000

22,800,000

Loan facility extinguished in exchange of common stock

624,944

Amount of debt cancelled upon issuance of common stock shares

16,900,000

Net proceeds from issuance of private placement

2,700,000

26,800,000

Issued warrants to purchase common stock

1,620,988

121,739

29,245

20,639

Exercise of price of common stock

5.75

30.21

22.13

Warrant term

'5 years

Warrant liability, fair value

6,466,000

Change in fair value of warrant liability

$494,000

$100,000

Warrant, extended expiration date

31-Dec-11

1-Apr-13

13-Apr-13

Percentage of reduction in number of shares exercisable

50.00%

45.00%

Number of warrants outstanding

14,623

13,160

13,163

Share price per share

$1.51

$0.79

$15.90

Expected life

'1 year

'2 years

Risk-free interest rate

0.50%

Volatility price

83.00%

Common_Stock_Reserved_Shares_o

Common Stock - Reserved Shares of Authorized but Unissued Common Stock (Detail)	Dec. 31, 2013	Dec. 31, 2012
Class of Stock [Line Items]	'	'
Total reserved shares of common stock	2,320,021	829,741
Outstanding common stock warrants [Member]	'	'
Class of Stock [Line Items]	'	'
Total reserved shares of common stock	1,742,727	28,208
Equity incentive plans [Member]	'	'
Class of Stock [Line Items]	'	'
Total reserved shares of common stock	577,294	140,474
Convertible preferred stock [Member]	'	'
Class of Stock [Line Items]	'	'
Total reserved shares of common stock	'	661,059

Stock_Plans_and_StockBased_Com2

Stock Plans and Stock-Based Compensation - Additional Information (Detail) (USD $)

12 Months Ended

1 Months Ended

12 Months Ended

0 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2010

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Sep. 30, 2013

Dec. 31, 2007

Dec. 31, 2013

Jan. 31, 2004

Stock Plan Activity [Member]

Restricted Stock Units [Member]

Scientific Advisory Board (SAB) and certain consultants [Member]

2013 Equity Incentive Plan [Member]

Incentive Awards [Member]

2003 Equity Incentive Plan [Member]

Directors And Employees [Member]

Nonqualified options to employees, directors, and consultants [Member]

Restricted Stock [Member]

10% stockholders [Member]

Exercisable for ten years, or 18 months after an initial public offering, if earlier. [Member]

Minimum [Member]

Maximum [Member]

Minimum [Member]

Maximum [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share based compensation arrangement by share based payment award, expiration period

'10 years

Share based compensation arrangement by share based payment award, percentage of common stock outstanding

100.00%

85.00%

Share based compensation arrangement by share based payment award, award vesting period

'60 months

'4 years

'5 years

'10 years

Share based compensation arrangement by share based payment award, exercise price percentage

110.00%

Number of shares, Outstanding

577,253

103,760

60,847

Change in exercise price

Stock option, Incremental expense resulting from modification

$200,000

Allocated share-based compensation expense

875,000

80,000

200,000

17,000

6,000

9,000

Shares available for grant

220,266

Increased in shares available for issuance

472,753

Expected dividend yield

0.00%

Total intrinsic value of options exercised

Fair value of options vested

900,000

100,000

Share based compensation, stock option, unamortized expense

$1,200,000

$200,000

Share based compensation, stock option, unamortized expense vesting period

'3 years 10 months 24 days

'2 years

Share reserved for issue

2,320,021

829,741

220,266

Exercisable price per share

Incentive awards vested percentage

100.00%

Stock option plan, Description

'Vest monthly over four years effective from their grant date.

Share price

Exercise price

$3.76

$3.97

Expected term

'6 years

'6 years 3 months

'6 years

Volatility rate

92.00%

100.00%

92.00%

Weighted-average grant date fair value outstanding

$238.50

$3.76

Number of stock units granted

Number of stock units vested

Number of stock units outstanding

Weighted-average remaining contractual term

'7 months 21 days

Share based compensation, shares authorized for issuance

1,230

Exercisable price

$9.55

$30.21

Exercisable period

'1 year 6 months

'10 years

Options to purchase common stock

6,833

3,145

Options to purchase common stock, unvested

14,623

4,555

Incentive award issued

2,335

Incentive awards outstanding, Unvested

2,335

Stock_Plans_and_StockBased_Com3

Stock Plans and Stock-Based Compensation - Summary of Stock Option Activity (Detail) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Shares Subject to Outstanding Options	'	'
Outstanding at the beginning of period	103,760	'
Options granted	487,697	'
Options exercised	-77	'
Options forfeited	-3,490	'
Options expired	-10,637	'
Outstanding as end of period	577,253	103,760
Vested and expected to vest	557,995	'
Exercisable	289,308	'
Weighted-Average Exercise Price of Options	'	'
Outstanding at the beginning of period	$34.19	'
Options granted	$5	'
Options exercised	$4.77	'
Options forfeited	$10.36	'
Options expired	$31.31	'
Outstanding as end of period	$7	$34.19
Vested and expected to vest	$7.07	'
Exercisable	$9.55	'
Weighted-Average Remaining Contractual Term (Years)	'	'
Outstanding	'9 years 6 months 26 days	'4 years 5 months 5 days
Vested and expected to vest	'9 years 6 months 22 days	'
Exercisable	'9 years 3 months	'
Aggregate Intrinsic Value (In Thousands)	'	'
Outstanding at the beginning of period	'	'
Outstanding as end of period	3	'
Vested and expected	3	'
Exercisable	$1	'

Stock_Plans_and_StockBased_Com4

Stock Plans and Stock-Based Compensation - Summary of Stock Options Outstanding (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Option Outstanding Number of Shares	577,253
Weighted-Average Remaining Contractual Term (Years)	'9 years 6 months 26 days
Options Exercisable Number of Shares	289,308
$4.77 [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Exercise Price	4.77
Option Outstanding Number of Shares	12,257
Weighted-Average Remaining Contractual Term (Years)	'7 years 7 months 13 days
Options Exercisable Number of Shares	8,815
$5.00 [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Exercise Price	5
Option Outstanding Number of Shares	548,544
Weighted-Average Remaining Contractual Term (Years)	'9 years 10 months 17 days
Options Exercisable Number of Shares	264,041
$15.90 [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Exercise Price	15.9
Option Outstanding Number of Shares	839
Weighted-Average Remaining Contractual Term (Years)	'3 months 7 days
Options Exercisable Number of Shares	839
$30.21 [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Exercise Price	30.21
Option Outstanding Number of Shares	8,638
Weighted-Average Remaining Contractual Term (Years)	'4 months 28 days
Options Exercisable Number of Shares	8,638
$39.75 [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Exercise Price	39.75
Option Outstanding Number of Shares	3,520
Weighted-Average Remaining Contractual Term (Years)	'3 months 7 days
Options Exercisable Number of Shares	3,520
$238.50 [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Exercise Price	238.5
Option Outstanding Number of Shares	3,455
Weighted-Average Remaining Contractual Term (Years)	'2 years 8 months 23 days
Options Exercisable Number of Shares	3,455

Stock_Plans_and_StockBased_Com5

Stock Plans and Stock-Based Compensation - Estimated Weighted-Average Grant Date Fair Value (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'
Expected term	'6 years	'6 years 3 months
Expected volatility	92.00%	100.00%
Risk-free interest rate	1.76%	1.01%
Expected dividend yield	0.00%	0.00%
Weighted-average grant date fair value per share	$3.76	$3.97

Stock_Plans_and_StockBased_Com6

Stock Plans and Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Stock-based compensation expense	$875	$80
Stock-based compensation expense	875	80
Research and development [Member]	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Stock-based compensation expense	184	26
General and administrative [Member]	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Stock-based compensation expense	$691	$54

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
Income Taxes - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Income Tax [Line Items]	'	'
Provision for income taxes	$0	$0
Net valuation allowance change	-1,800,000	4,700,000
Cumulative change in ownership	50.00%	'
Cumulative change in ownership period	'3 years	'
Significant change to its unrecognized tax benefits over the next twelve months	0	'
Income tax examination years	'The tax years 1998 through 2013 remain open to examination by the major taxing authorities.	'
Domestic Tax Authority [Member]	'	'
Income Tax [Line Items]	'	'
Net operating loss carryforward	152,100,000	'
Domestic Tax Authority [Member] \| Minimum [Member]	'	'
Income Tax [Line Items]	'	'
NOL carry forward expiry date	'2024	'
Domestic Tax Authority [Member] \| Maximum [Member]	'	'
Income Tax [Line Items]	'	'
NOL carry forward expiry date	'2033	'
Domestic Tax Authority [Member] \| Research and Development Tax Credit Carryforward [Member]	'	'
Income Tax [Line Items]	'	'
Research and development tax credit carry forwards	6,200,000	'
State and Local Jurisdiction [Member]	'	'
Income Tax [Line Items]	'	'
Net operating loss carryforward	152,200,000	'
State and Local Jurisdiction [Member] \| Minimum [Member]	'	'
Income Tax [Line Items]	'	'
NOL carry forward expiry date	'2014	'
State and Local Jurisdiction [Member] \| Maximum [Member]	'	'
Income Tax [Line Items]	'	'
NOL carry forward expiry date	'2033	'
State and Local Jurisdiction [Member] \| Research and Development Tax Credit Carryforward [Member]	'	'
Income Tax [Line Items]	'	'
Research and development tax credit carry forwards	$3,200,000	'

Income_Taxes_Components_of_Def

Income Taxes - Components of Deferred Tax Assets (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets:	'	'
Federal and state net operating loss carryforwards	$60,569	$62,745
Capitalized research and development	22,349	22,490
Federal and state tax credit carryforwards	6,600	6,153
Other	1,313	1,200
Total deferred tax assets	90,831	92,588
Valuation allowance	-90,831	-92,588
Net deferred tax assets	'	'

Income_Taxes_Summary_of_Reconc

Income Taxes - Summary of Reconciliation of Expected Statutory Federal Income Tax Provision to Actual Income Tax Provision (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]	'	'
Expected income tax benefit at federal statutory tax rate	($3,424)	($3,826)
Net operating loss reduction	4,441	'
Change in valuation allowance	-1,757	4,668
State income taxes, net of federal benefit	583	-763
Permanent items	555	54
Research credits	-396	'
Other, net	-2	-133
Income tax (benefit) expense	'	'

Income_Taxes_Summary_of_Gross_

Income Taxes - Summary of Gross Unrecognized Tax Benefits (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]	'	'
Balance at beginning of period	$1,747	$1,711
Increases related to prior year tax positions	65	'
Increases related to 2012 tax positions	53	36
Balance at end of period	$1,865	$1,747

RelatedParty_Transactions_Addi

Related-Party Transactions - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Related Party Transactions [Abstract]	'	'
Advisory fee paid to related party	$45,000	$60,000

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (Clinical Research and Development Agreement [Member], USD $)	12 Months Ended	1 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Feb. 28, 2014
	Dec. 31, 2013	Subsequent Event [Member]
Subsequent Event [Line Items]	'	'
Total anticipated cost exceeds on research and development services	'	$8
Term period of master services agreement	'	'5 years
Notice period for termination of master service agreement	'30 days	'
Terms of master service agreement	'	'The Company may terminate the master services agreement or any individual work order of the master services agreement on thirty (30) days written notice, or immediately in the event of any safety risk associated with the services being performed. In addition, either party may terminate the Agreement or any applicable work order upon thirty (30) days written notice for a material breach by the other party.