Kythera Biopharmaceuticals (KYTH) Inactive 10-K17 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. 01, 2014	Jun. 28, 2013
Document and Entity Information	'	'	'
Entity Registrant Name	'KYTHERA BIOPHARMACEUTICALS INC	'	'
Entity Central Index Key	'0001436304	'	'
Document Type	'10-K	'	'
Document Period End Date	31-Dec-13	'	'
Amendment Flag	'false	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'No	'	'
Entity Voluntary Filers	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Filer Category	'Accelerated Filer	'	'
Entity Public Float	'	'	$353,676,180
Entity Common Stock, Shares Outstanding	'	21,864,232	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'

Balance_Sheets

Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
Current assets:	'	'
Cash and cash equivalents	$111,518,000	$79,311,000
Restricted cash, current portion	5,062,000	7,657,000
Marketable securities	55,540,000	'
Prepaid expenses and other current assets	1,156,000	621,000
Total current assets	173,276,000	87,589,000
Property and equipment, net	94,000	275,000
Restricted cash-net of current portion	'	8,321,000
Other assets	37,000	37,000
Total assets	173,407,000	96,222,000
Current liabilities:	'	'
Accounts payable	3,228,000	2,152,000
Accrued personnel costs	3,114,000	2,173,000
Accrued costs for services	3,191,000	4,862,000
Accrued interest	375,000	22,000
Notes payable, current portion	5,526,000	1,160,000
Deferred development funds, current portion	2,147,000	5,853,000
Total current liabilities	17,581,000	16,222,000
Notes payable-net of current portion	5,979,000	2,764,000
Deferred development funds-net of current portion	'	8,321,000
Deferred rent	8,000	9,000
Total liabilities	23,568,000	27,316,000
Commitments and contingencies	'	'
Stockholders' equity:	'	'
Preferred stock, $0.00001 par value, 5,000,000 shares authorized and none issued and outstanding	'	'
Common stock, $0.00001 par value, 300,000,000 shares authorized, 21,745,000 and 18,325,000 shares issued and outstanding at December 31, 2013 and 2012, respectively	'	'
Additional paid in capital	322,052,000	189,212,000
Accumulated other comprehensive income	4,000	'
Accumulated deficit	-172,217,000	-120,306,000
Total stockholders' equity	149,839,000	68,906,000
Total liabilities and stockholders' equity	$173,407,000	$96,222,000

Balance_Sheets_Parenthetical

Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Preferred stock par value (in dollars per share)	$0.00	$0.00
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$0.00	$0.00
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	21,745,000	18,325,000
Common stock, shares outstanding	21,745,000	18,325,000

Statements_of_Operations_and_C

Statements of Operations and Comprehensive Loss (USD $)	12 Months Ended
Statements of Operations and Comprehensive Loss (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statements of Operations and Comprehensive Loss	'	'	'
License income	'	$19,687,000	$12,985,000
Sublicense expense	'	1,936,000	1,188,000
Gross margin	'	17,751,000	11,797,000
Operating expenses:	'	'	'
Research and development	33,974,000	43,184,000	15,766,000
General and administrative	16,092,000	10,505,000	6,879,000
Total operating expenses	50,066,000	53,689,000	22,645,000
Loss from operations	-50,066,000	-35,938,000	-10,848,000
Interest income	135,000	'	'
Interest expense	-1,980,000	-441,000	-75,000
Warrant and other income (expense), net	'	-420,000	-229,000
Net loss	-51,911,000	-36,799,000	-11,152,000
Other comprehensive income:	'	'	'
Unrealized net gain on marketable securities	4,000	'	'
Comprehensive loss	($51,907,000)	($36,799,000)	($11,152,000)
Per share information:	'	'	'
Net loss, basic and diluted (in dollars per share)	($2.71)	($7.47)	($7.98)
Basic and diluted weighted average shares outstanding (in shares)	19,150,000	4,924,000	1,398,000

Statements_of_Redeemable_Conve

Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (USD $)	Total	Common Stock	Additional Paid in Capital	Accumulated Other Comprehensive Income (loss)	Accumulated Deficit	Series A Redeemable Convertible Preferred Stock	Series B Redeemable Convertible Preferred Stock	Series C Redeemable Convertible Preferred Stock	Series D Redeemable Convertible Preferred Stock
	USD ($)	Common Stock	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)
Balance at Dec. 31, 2010	($70,747,000)	'	$1,608,000	'	($72,355,000)	$902,000	$30,193,000	$40,205,000	'
Balance (in shares) at Dec. 31, 2010	'	1,394,000	'	'	'	1,806,000	3,981,000	3,023,000	'
Increase (Decrease) in Stockholders' Equity	'	'	'	'	'	'	'	'	'
Issuance of common stock in connection with exercise of stock options	18,000	'	18,000	'	'	'	'	'	'
Issuance of common stock in connection with exercise of stock options (in shares)	'	12,000	'	'	'	'	'	'	'
Re-purchase of common stock	-1,000	'	-1,000	'	'	'	'	'	'
Re-purchase of common stock (in shares)	'	-7,000	'	'	'	'	'	'	'
Issuance of preferred stock for cash	'	'	'	'	'	'	'	'	36,287,000
Issuance of preferred stock for cash (in shares)	'	'	'	'	'	'	'	'	2,692,000
Compensation expense related to stock options	858,000	'	858,000	'	'	'	'	'	'
Other comprehensive income	0	'	'	'	'	'	'	'	'
Net loss	-11,152,000	'	'	'	-11,152,000	'	'	'	'
Balance at Dec. 31, 2011	-81,024,000	'	2,483,000	'	-83,507,000	902,000	30,193,000	40,205,000	36,287,000
Balance (in shares) at Dec. 31, 2011	'	1,399,000	'	'	'	1,806,000	3,981,000	3,023,000	2,692,000
Increase (Decrease) in Stockholders' Equity	'	'	'	'	'	'	'	'	'
Issuance of common stock in connection with exercise of stock options	123,000	'	123,000	'	'	'	'	'	'
Issuance of common stock in connection with exercise of stock options (in shares)	'	51,000	'	'	'	'	'	'	'
Issuance of stock for services	43,000	'	43,000	'	'	'	'	'	158,000
Issuance of stock for services (in shares)	'	5,000	'	'	'	'	'	'	11,000
Issuance of common stock in October 2012 at $22.50 per share for services	1,414,000	'	1,414,000	'	'	'	'	'	'
Issuance of common stock in October 2012 at $22.50 per share for services (in shares)	'	63,000	'	'	'	'	'	'	'
Compensation expense related to stock options	1,816,000	'	1,816,000	'	'	'	'	'	'
Issuance of shares of common stock at $45.75 and $16.00 per share, net of issuance cost of $8,591,000 and $8,481,000 for the year ended December 31, 2013 and 2012 respectively	72,479,000	'	72,479,000	'	'	'	'	'	'
Issuance of shares of common stock at $45.75 and $16.00 per share, net of issuance cost of $8,591,000 and $8,481,000 for the year ended December 31, 2013 and 2012 respectively	'	5,060,000	'	'	'	'	'	'	'
Conversion of convertible preferred stock into common stock	107,743,000	'	107,743,000	'	'	-902,000	-30,193,000	-40,205,000	-36,445,000
Conversion of convertible preferred stock into common stock (in shares)	'	11,545,000	'	'	'	-1,806,000	-3,981,000	-3,023,000	-2,703,000
Reclassification of Preferred Stock Warrant Liability to additional paid in capital	3,101,000	'	3,101,000	'	'	'	'	'	'
Other comprehensive income	0	'	'	'	'	'	'	'	'
Issuance of common stock due to net exercise of warrants (in shares)	'	201,000	'	'	'	'	'	'	'
Issuance of common stock due to warrants exercised for cash	10,000	'	10,000	'	'	'	'	'	'
Issuance of common stock due to warrants exercised for cash (in shares)	'	1,000	'	'	'	'	'	'	'
Net loss	-36,799,000	'	'	'	-36,799,000	'	'	'	'
Balance at Dec. 31, 2012	68,906,000	'	189,212,000	'	-120,306,000	'	'	'	'
Balance (in shares) at Dec. 31, 2012	'	18,325,000	'	'	'	'	'	'	'
Increase (Decrease) in Stockholders' Equity	'	'	'	'	'	'	'	'	'
Issuance of common stock in connection with exercise of stock options	1,338,000	'	1,338,000	'	'	'	'	'	'
Issuance of common stock in connection with exercise of stock options (in shares)	'	495,000	'	'	'	'	'	'	'
Issuance of stock for services	101,000	'	101,000	'	'	'	'	'	'
Issuance of stock for services (in shares)	'	5,000	'	'	'	'	'	'	'
Compensation expense related to stock options	6,402,000	'	6,402,000	'	'	'	'	'	'
Issuance of shares of common stock at $45.75 and $16.00 per share, net of issuance cost of $8,591,000 and $8,481,000 for the year ended December 31, 2013 and 2012 respectively	124,999,000	'	124,999,000	'	'	'	'	'	'
Issuance of shares of common stock at $45.75 and $16.00 per share, net of issuance cost of $8,591,000 and $8,481,000 for the year ended December 31, 2013 and 2012 respectively	'	2,920,000	'	'	'	'	'	'	'
Other comprehensive income	4,000	'	'	4,000	'	'	'	'	'
Net loss	-51,911,000	'	'	'	-51,911,000	'	'	'	'
Balance at Dec. 31, 2013	$149,839,000	'	$322,052,000	$4,000	($172,217,000)	'	'	'	'
Balance (in shares) at Dec. 31, 2013	'	21,745,000	'	'	'	'	'	'	'

Statements_of_Redeemable_Conve1

Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) (USD $)	1 Months Ended			12 Months Ended		1 Months Ended
	Apr. 30, 2013	Oct. 31, 2012	Jan. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Jul. 31, 2012	Aug. 31, 2011
	Common Stock	Common Stock	Common Stock	Common Stock	Common Stock	Series D Redeemable Convertible Preferred Stock	Series D Redeemable Convertible Preferred Stock
Per share price of stock issued (in dollars per share)	$20.14	$22.50	$8.22	$45.75	$16	$13.90	$13.90
Issuance costs	'	'	'	$8,591,000	$8,481,000	'	$1,138,000
Issuance of common stock (in shares)	'	'	'	2,920,000	5,060,000	'	'

Statements_of_Cash_Flows

Statements of Cash Flows (USD $)	12 Months Ended
Statements of Cash Flows (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities	'	'	'
Net loss	($51,911,000)	($36,799,000)	($11,152,000)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:	'	'	'
Amortization of premium on marketable securities	572,000	'	'
Amortization of debt issuance cost	340,000	272,000	'
Amortization of redeemable convertible preferred stock warrant value	'	'	71,000
Depreciation	223,000	635,000	54,000
Loss on disposal of property and equipment	0	0	4,000
Revaluation of redeemable convertible preferred stock warrants	'	422,000	229,000
Stock-based compensation	6,503,000	1,857,000	858,000
Issuance of stock for licensor payment	'	1,572,000	'
Changes in assets and liabilities:	'	'	'
Prepaid expenses and other current assets	-183,000	561,000	-809,000
Restricted cash	10,916,000	-8,575,000	14,416,000
Deferred licensor payment	'	352,000	1,188,000
Other assets	'	-6,000	-12,000
Accounts payable and other accrued liabilities	699,000	3,203,000	80,000
Deferred revenue	'	-3,847,000	-12,984,000
Deferred development funds	-12,027,000	9,223,000	-14,652,000
Payable to licensor	'	-1,560,000	'
Deferred rent	-1,000	2,000	2,000
Net cash used in operating activities	-44,869,000	-32,688,000	-22,707,000
Investing activities	'	'	'
Purchases of marketable securities	-63,832,000	'	'
Proceeds from sales of marketable securities	7,372,000	'	'
Investment in property and equipment	-42,000	-190,000	-696,000
Net cash used in investing activities	-56,502,000	-190,000	-696,000
Financing activities	'	'	'
Borrowings on credit facility	10,000,000	5,000,000	'
Repayment of notes payable	-2,759,000	'	'
Proceeds from public offering, net of issuance costs	124,999,000	72,479,000	'
Proceeds from common stock option and warrant exercises	1,338,000	133,000	17,000
Net proceeds from issuance of convertible preferred stock	'	'	36,287,000
Net cash provided by financing activities	133,578,000	77,612,000	36,304,000
Net increase in cash and cash equivalents	32,207,000	44,734,000	12,901,000
Cash and cash equivalents at beginning of period	79,311,000	34,577,000	21,676,000
Cash and cash equivalents at end of period	111,518,000	79,311,000	34,577,000
Supplemental disclosures	'	'	'
Issuance of redeemable convertible preferred stock warrants for senior loan facility commitment	'	534,000	885,000
Reclassification of warrants to purchase common stock	'	3,101,000	'
Conversion of convertible preferred stock to common stock	'	107,743,000	'
Issuance of redeemable convertible preferred stock for licensor payment	'	158,000	'
Issuance of common stock for licensor payment	'	1,414,000	'
Issuance of common stock for services rendered	101,000	43,000	'
Interest expense paid in cash	$1,288,000	$147,000	'

Organization_and_Basis_of_Pres

Organization and Basis of Presentation	12 Months Ended
Organization and Basis of Presentation	Dec. 31, 2013
Organization and Basis of Presentation	'
Organization and Basis of Presentation	'

	1. Organization and Basis of Presentation

	KYTHERA Biopharmaceuticals, Inc. ("KYTHERA" or the "Company") is a clinical-stage biopharmaceutical company focused on the discovery, development and commercialization of novel prescription products for the aesthetic medicine market. The Company's objective is to develop first-in-class, prescription aesthetic products using an approach that relies on the scientific rigor of biotechnology to address unmet needs in the rapidly-growing market for aesthetic medicine. The Company's initial focus is on the facial aesthetics market, which comprises the majority of the aesthetics medicine market. The Company's product candidate, ATX-101, is a potential first-in-class, injectable drug in late stage clinical development for the reduction of submental fat, which commonly presents as an undesirable "double chin."

	KYTHERA was originally incorporated in Delaware in June 2004 under the name Dermion, Inc. It commenced operations in August 2005 and its name was changed to AESTHERx, Inc. In July 2006, the Company changed its name to KYTHERA Biopharmaceuticals, Inc.

	Since commencement of operations in August 2005, the Company has devoted substantially all its efforts to the development of ATX-101, recruiting personnel and raising capital. In 2010, the Company entered into a License Agreement with Bayer Consumer Care AG and a Services, Research, Development and Collaboration Agreement with Bayer's Affiliate, Intendis GmbH, collectively referred to as the collaboration arrangement with Bayer. Bayer Consumer Care AG and Intendis GmbH are referred to jointly as Bayer.

	The accompanying financial statements for the years ended December 31, 2013, 2012, and 2011 have been prepared on a going-concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business for the foreseeable future. Since inception in 2004, the Company has not been profitable and has incurred operating losses in each year. The Company has a limited operating history upon which you can evaluate its business and prospects. The Company has not generated any revenue from product sales to date and will continue to incur significant research and development and other expenses related to its ongoing operations. The Company has recorded net losses of $51,911,000, $36,799,000 and $11,152,000 for the years ended December 31, 2013, 2012 and 2011, respectively, and had an accumulated deficit of $172,217,000 and $120,306,000 as of December 31, 2013 and 2012, respectively. The Company has funded its operations primarily through the sale and issuance of common and preferred stock, convertible debt, and amounts received pursuant to the collaboration arrangement with Bayer and borrowings under its credit facility. Net working capital at December 31, 2013 and 2012, was $155,695,000 and $71,367,000, respectively. The Company expects to continue to incur losses for the foreseeable future. At December 31, 2013, the Company had capital resources consisting of cash and cash equivalents, marketable securities and restricted cash of $172,120,000, of which $5,062,000 was restricted. At December 31, 2013, the Company had no further borrowing capacity under its existing credit facility.

	On September 11, 2012, the Board of Directors approved a 1-for-2.6443 reverse stock split of the Company's capital stock. All share and per share information included in the accompanying financial statements has been adjusted to reflect this reverse stock split.

	On October 16, 2012, the Company completed its initial public offering ("IPO") of 5,060,000 shares of common stock, which includes the exercise in full by the underwriters of their option to purchase up to 660,000 additional shares of common stock, at an offering price of $16.00 per share. The Company received net proceeds of approximately $72,479,000, after deducting underwriting discounts, commissions and offering related transaction costs. In connection with the IPO, the Company's outstanding shares of redeemable convertible preferred stock were automatically converted into 11,545,000 shares of common stock and warrants exercisable for redeemable convertible preferred stock were automatically converted into warrants exercisable for 365,000 shares of common stock, resulting in the reclassification of the related redeemable convertible preferred stock warrant liability of $3,101,000 to additional paid-in capital.

	In connection with the completion of its IPO, on October 16, 2012, the Company filed an amended and restated certificate of incorporation and bylaws, which, among other things, changed the number of authorized shares of common stock to 300,000,000 shares and preferred stock to 5,000,000 shares.

	On October 15, 2013, the Company completed its secondary offering of 2,623,000 shares of common stock at an offering price of $45.75 per share. On November 12, 2013, the underwriters purchased an additional 297,000 shares of common stock pursuant to their option to purchase additional shares. The Company received aggregate net proceeds of approximately $124,999,000, after deducting the underwriting discounts, commissions and offering related transaction costs.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2013
Summary of Significant Accounting Policies	'
Summary of Significant Accounting Policies	'

	2. Summary of Significant Accounting Policies

	Basis of Presentation

	The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP.

	Reclassifications

	Certain prior year amounts have been reclassified to conform to the current year presentation.

	Use of Estimates

	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the financial statements and accompanying notes. Actual results could materially differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including: expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. 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. This process may result in actual results differing materially from those estimated amounts used in the preparation of the financial statements.

	Segment Reporting

	To date, the Company has viewed its operations and manages its business as one segment operating primarily in the United States.

	Cash and Cash Equivalents and Marketable Securities

	All highly liquid securities with maturities of 90 days or less from the date of purchase are considered to be cash equivalents. As of December 31, 2013 and 2012, cash and cash equivalents are comprised of funds invested in cash and money market accounts. The Company maintains cash balances in excess of amounts insured by the Federal Deposit Insurance Corporation, or FDIC. The accounts are monitored by management to mitigate the risk.

	Investments with maturities of more than 90 days from the date of purchase are considered marketable securities. Marketable securities are stated at fair value. The Company has classified the entire marketable securities portfolio as available-for-sale securities. Accordingly, any unrealized gain or loss on the investments is reported as a component of accumulated other comprehensive income (loss). The amortized cost of these securities is adjusted for amortization of premiums and accretion of discounts to maturity, as applicable. Such amortizations and accretions are included in interest income. The entire marketable securities portfolio is considered available for use in current operations and, accordingly, all such investments are considered current assets although the stated maturity of individual investments may be one year or more beyond the balance sheet date.

	Realized gains and losses on sales of marketable securities are determined on a specific identification basis and reported in interest income. When securities are sold, any associated unrealized gain or loss previously reported in accumulated other comprehensive income (loss) is reclassified out of stockholders' equity and recorded in the statement of operations and comprehensive loss for the period. Accrued interest and dividends are included in interest income.

	On a quarterly basis, the Company reviews its available-for-sale securities for other-than temporary declines in fair value below the amortized cost basis. This evaluation is based on a number of factors including the length of time and extent to which the fair value has been below the cost basis and any adverse conditions related specifically to the security, including any changes to the credit rating of the security. If the Company concludes that an other-than- temporary impairment exists, it recognizes an impairment charge to reduce the investment to fair value and records the related charge as a reduction of interest income. No impairment charges were recognized during the year ended December 31, 2013.

	As of December 31, 2012 and 2011, the Company did not have any marketable securities. There were no realized gains or losses from the sale of marketable securities for the years ended December 31, 2012 or 2011 and were immaterial for the year ended December 31, 2013.

	Restricted Cash

	Restricted cash of $5,602,000 and $15,978,000 at December 31, 2013 and 2012, respectively, represents restricted cash received through the collaboration arrangement with Bayer that will be used to fund certain further global development activities of ATX-101. See Note 8, "Commitments, Collaborations and Contingencies."

	Payments the Company received to fund collaboration efforts under the terms of the collaboration agreement with Bayer were recorded as restricted cash and deferred development funds, and are recognized as an offset to development expenses as the restricted cash is utilized to fund such development activities.

	Property and Equipment

	Property and equipment are recorded at historical cost and consisted of the following:


		December 31,
		2013			2012
	Cameras	$	923,000		$	923,000
	Computer hardware and electronics		182,000			147,000
	Furniture and fixtures		234,000			227,000
	Software		21,000			21,000


			1,360,000			1,318,000
	Less accumulated depreciation		(1,266,000	)		(1,043,000	)


		$	94,000		$	275,000





	Depreciation is recorded using the straight-line method over the estimated useful lives of the assets (one to five years). The Company reviews its property and equipment assets for impairment in value whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The Company disposed of $54,000 of computer hardware and electronics for the year ended December 31, 2011, with a recognized loss at disposal of $4,000. No disposals were made during the years ended December 31, 2013 and 2012 and no loss on disposal was recognized during the years ended December 31, 2013 and 2012.

	Cameras were used in our clinical trials, are fully depreciated as of December 31, 2013 and are being held for disposal.

Concentration of Credit Risk

Financial instruments, which potentially subject the Company to significant concentrations of credit risk, consist primarily of cash and cash equivalents and marketable securities. The primary objectives for the Company's investment portfolio are the preservation of capital and the maintenance of liquidity. We do not enter into any investment transaction for trading or speculative purposes.

The Company's investment policy limits investments to certain types of instruments such as certificates of deposit, money market instruments, obligations issued by U.S. government and U.S. government agencies and corporate debt securities and places restrictions on maturities and concentration by type and issuer. The Company maintains cash balances in excess of amounts insured by the FDIC. The accounts are monitored by management to mitigate the risk.

Stock-Based Compensation

The Company accounts for all stock-based payments issued to employees and directors using an option pricing model for estimating fair value. Accordingly, stock-based compensation expense is measured based on the estimated fair value of the awards on the date of grant, net of forfeitures. Compensation expense is recognized for the portion that is ultimately expected to vest over the period during which the recipient renders the required services to the Company using the straight-line single option method.

In accordance with authoritative guidance, the fair value of non-employee stock based awards is remeasured as the awards vest, and the resulting increase in fair value, if any, is recognized as expense in the period the related services are rendered.

Redeemable Convertible Preferred Stock Warrants

Prior to the Company's IPO, freestanding warrants that related to the purchase of redeemable convertible preferred stock were classified as liabilities and recorded at fair value each reporting period regardless of the timing of the redemption feature or the redemption price or the likelihood of redemption. The warrants were subject to remeasurement at each balance sheet date and any change in fair value was recognized as a component of warrant and other income (expense), net. Pursuant to the terms of these warrants, upon the conversion of the class of preferred stock underlying the warrant, the warrants automatically became exercisable for shares of the Company's common stock based upon the conversion ratio of the underlying class of preferred stock. The consummation of the Company's IPO resulted in the conversion of all classes of the Company's preferred stock into common stock. Upon such conversion of the underlying classes of preferred stock, the warrants were reclassified as a component of equity and were no longer subject to remeasurement.

Fair Value of Financial Instruments

The carrying amounts reported in the accompanying financial statements for accounts payable and accrued liabilities approximate their fair value because of the short-term nature of these accounts. The fair value of cash equivalents, marketable securities and the notes payable are discussed in Note 9, "Fair Value Measurements."

Revenue Recognition

The Company recognizes revenue when all of the following four criteria are present: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; the fee is fixed or determinable; and collectability is reasonably assured.

For arrangements that involve the delivery of more than one element, each product, service and/or right to use assets is evaluated to determine whether it qualifies as a separate unit of accounting. This determination is based on whether the deliverable has "stand-alone value" to the customer. The consideration that is fixed or determinable is then allocated to each separate unit of accounting based on the relative selling price of each deliverable. The estimated selling price of each deliverable is determined using the following hierarchy of values: (i) vendor-specific objective evidence of fair value, (ii) third-party evidence of selling price (TPE) and (iii) best estimate of selling price (BESP). The BESP reflects our best estimate of what the selling price would be if the deliverable was regularly sold by us on a stand-alone basis. In most cases we expect to use TPE or BESP for allocating consideration to each deliverable. The consideration allocated to each unit of accounting is recognized as the related goods or services are delivered, limited to the consideration that is not contingent upon future deliverables. Analyzing the arrangement to identify deliverables requires the use of judgment, and each deliverable may be an obligation to deliver services, a right or license to use an asset, or another performance obligation.

The Company's revenue is related to the license agreement with Bayer executed in 2010. This agreement provided for various types of payments, including non-refundable upfront license fees, milestone payments, and future royalties on Bayer's net product sales of ATX-101.

The Company received a non-refundable upfront license payment of approximately $21,319,000 from Bayer upon execution of the license agreement. The terms of the collaboration arrangement with Bayer included continuing performance obligations and development and clinical manufacturing supply obligations that were conditions to Bayer's decision to pursue continued development and regulatory approval for ATX-101. Due to these ongoing performance obligations, the Company determined that the license did not have stand-alone value. The Company also did not have objective and reliable evidence of the fair value of these undelivered obligations. Accordingly, amounts received upfront under the license agreement were recorded as deferred revenue and were recognized on a straight-line basis over the expected period of substantial involvement in these collaboration activities, which were completed as of May 31, 2012. The period over which these activities were to be performed was based upon management's estimate of the period to complete the development activities required to be conducted relative to the upfront license fee and development funds received from Bayer.

The Company recognizes revenue from milestone payments when earned, provided that (i) the milestone event is substantive in that it can only be achieved based in whole or in part on either the entity's performance or on the occurrence of a specific outcome resulting from the entity's performance and its achievability was not reasonably assured at the inception of the collaboration arrangement and (ii) the Company does not have ongoing performance obligations related to the achievement of the milestone earned and (iii) it would result in additional payments being due to the Company. Milestone payments are considered substantive if all of the following conditions are met: the milestone payment is non-refundable; achievement of the milestone was not reasonably assured at the inception of the arrangement; substantive effort is involved to achieve the milestone; and the amount of the milestone appears reasonable in relation to the effort expended, the other milestones in the arrangement and the related risk associated with the achievement of the milestone. Any amounts received under the collaboration arrangement in advance of performance, if deemed substantive, are recorded as deferred revenue and recognized as revenue as the Company completes its performance obligations.

Research and Development Costs

Major components of research and development (R&D) costs include cash compensation, stock-based compensation, pre-clinical studies, clinical trials and related clinical manufacturing, materials and supplies, and fees paid to consultants and other entities that conduct certain research and development activities on the Company's behalf. R&D costs, including upfront fees and milestones paid to collaborators, are expensed as goods are received or services rendered. Costs to acquire technologies to be used in research and development that have not reached technological feasibility and have no alternative future use are also expensed as incurred. Costs incurred in connection with clinical trial activities for which the underlying nature of the activities themselves do not directly relate to active research and development, such as costs incurred for market research and focus groups linked to clinical strategy as well as costs to build the Company's brand, are not included in R&D costs but are reflected as general and administrative expenses.

The Company enters into agreements with various research institutions, contract laboratories, contract manufacturers and consultants. These agreements are generally on a fee-for-service basis and are cancelable.

Clinical Trial Accruals

As part of the process of preparing its financial statements, the Company is required to estimate its expenses resulting from its obligations under contracts with vendors and consultants and clinical site agreements in connection with conducting clinical trials. The financial terms of these contracts are subject to negotiations which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to us under such contracts. 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 expended. The Company accounts for these expenses according to the progress of the trial as measured by patient progression and the timing of various aspects of the trial. The Company determines accrual estimates through financial models taking into account discussion with applicable personnel and outside service providers as to the progress or state of consummation of trials, or the services completed. During the course of a clinical trial, the Company adjusts its rate of clinical expense recognition if actual results differ from its estimates. The Company makes estimates of its accrued expenses as of each balance sheet date in its financial statements based on the facts and circumstances known to us at that time. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in us reporting amounts that are too high or too low for any particular period. Through December 31, 2013, there have been no material adjustments to the Company's prior period estimates of accrued expenses for clinical trials. The Company's clinical trial accrual is dependent in part upon the timely and accurate reporting of contract research organizations and other third-party vendors.

Basic and Diluted Net Loss Per Common Share

Basic net loss per common share is computed by dividing the net loss by the weighted average number of common shares outstanding during the period, excluding the dilutive effects of converting redeemable preferred stock, warrants to purchase redeemable convertible preferred stock or common stock and options outstanding. Diluted net loss per common share is computed by dividing the net loss by the sum of the weighted average number of common shares outstanding during the period plus the potential dilutive effects of redeemable convertible preferred stock, warrants to purchase redeemable convertible preferred stock or common stock and options outstanding during the period calculated in accordance with the treasury stock method. Because the impact of these items is anti-dilutive during periods of net loss, there was no difference between the weighted average number of shares used to calculate basic and diluted net loss per common share for the years ended December 31, 2013, 2012 and 2011. The calculation of weighted average diluted shares outstanding excludes the dilutive effect of redeemable convertible preferred stock, warrants to purchase redeemable convertible preferred stock and options to purchase common stock, as the impact of such items are anti-dilutive during periods of net loss. Shares excluded from the calculation, prior to the use of the treasury stock method, unweighted, were 2,335,000, 1,956,000 and 13,334,000 at December 31, 2013, 2012 and 2011, respectively.

Income Taxes

The Company accounts for income taxes under the asset and liability method, which requires, among other things, that deferred income taxes be provided for temporary differences between the tax bases of the Company's assets and liabilities and their financial statement reported amounts. A valuation allowance is recorded when it is more likely than not that some portion or all of a deferred tax asset will not be realized. Management has considered estimated future taxable income and ongoing prudent and feasible tax planning strategies in assessing the amount of the valuation allowance. When the Company establishes or reduces the valuation allowance against its deferred tax assets, its provision for income taxes will increase or decrease, respectively, in the period such determination is made.

Additionally, the Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities based on the technical merits of the position. The tax benefit recognized in the financial statements for a particular tax position is based on the largest benefit that is more likely than not to be realized upon settlement. Accordingly, the Company establishes reserves for uncertain tax positions.

Comprehensive Income (Loss)

Comprehensive income (loss) is comprised of net loss and other comprehensive income (loss). For the year ended December 31, 2013, the only component of other comprehensive income (loss) relates to net unrealized gains and losses on marketable securities. We had no other comprehensive income (loss) for the years ended December 31, 2012 and 2011.

Effective January 1, 2013, we adopted a new accounting standard that requires increased disclosure regarding amounts that are reclassified out of accumulated other comprehensive income subsequent to January 1, 2013. There were no reclassifications out of accumulated other comprehensive income during the year ended December 31, 2013.

Collaboration Arrangements

From time to time, we enter into certain collaboration arrangements with third parties regarding the research and development, manufacture and/or commercialization of products and product candidates. These collaborations generally provide for non-refundable, upfront license fees, research and development and commercial performance milestone payments, cost sharing and royalty payments. The collaboration agreements with third parties are performed on a "best efforts" basis with no guarantee of either technological or commercial success. The Company evaluates whether an arrangement is a collaboration arrangement at its inception based on the facts and circumstances specific to the arrangement. The Company reevaluates whether an arrangement qualifies or continues to qualify as a collaboration arrangement whenever there is a change in the anticipated or actual ultimate commercial success of the endeavor. See Note 8, "Commitments, Collaborations and Contingencies."

Recent Accounting Pronouncements

In July 2013, a new accounting standard was issued that requires companies to present in the financial statements an unrecognized tax benefit as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward. To the extent the tax benefit is not available at the reporting date under the governing tax law or if the entity does not intend to use the deferred tax asset for such purpose, the unrecognized tax benefit should be presented as a liability and not combined with deferred tax assets. The standard is required to be adopted prospectively beginning on January 1, 2014 and may be applied retrospectively to each prior reporting period presented. The Company does not believe the adoption of this accounting standard will have a material impact on the Company's financial statements and related disclosures.

Marketable_Securities

Marketable Securities	12 Months Ended
Marketable Securities	Dec. 31, 2013
Marketable Securities	'
Marketable Securities	'

	3. Marketable Securities

	Our marketable securities held as of December 31, 2013 are summarized below:


		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair Value
				Gains		Losses
	U.S. government agency securities	$	2,000,000	$	3,000	$	—		$	2,003,000
	Corporate debt securities:
	Financial		33,192,000		13,000		(5,000	)		33,200,000
	Industrial		11,081,000		2,000		(3,000	)		11,080,000
	Other		9,263,000		—		(6,000	)		9,257,000


	Total available-for-sale securities	$	55,536,000	$	18,000	$	(14,000	)	$	55,540,000





	As of December 31, 2012 the Company did not have any marketable securities. There were no realized gains or losses from the sale of marketable securities for the year ended December 31, 2012 and were immaterial for the year ended December 31, 2013. All of our available-for-sale investments that were in an unrealized loss position have been in a continuous unrealized loss position for less than 12 months and had an aggregate fair value of $20,277,000 as of December 31, 2013. The unrealized losses related to corporate debt securities, which the Company plans to hold until maturity, and it is more likely than not that the Company will not be required to sell prior to maturity. Due to the limited duration and severity of the loss, as well as the nature of corporate debt securities, the Company does not consider the investments to be other-than-temporarily impaired at December 31, 2013.

	The maturities of our marketable securities available-for-sale as of December 31, 2013 are as follows:


		Amortized		Estimated
		Cost		Fair Value
	Mature in one year or less	$	33,279,000	$	33,293,000
	Mature after one year through two years		22,257,000		22,247,000


		$	55,536,000	$	55,540,000

Bridge_Financing

Bridge Financing	12 Months Ended
Bridge Financing	Dec. 31, 2013
Bridge Financing	'
Bridge Financing	'

	4. Bridge Financing

	In January 2006, the Company entered into bridge financing transactions by issuing convertible promissory notes and warrants, for aggregate proceeds of $8,051,000 from certain existing and new investors. The convertible notes bore interest at 8% and were automatically convertible into shares of the Company's preferred stock upon the occurrence of a qualified preferred stock financing as described in the convertible promissory note agreement. The estimated fair value of the warrants, totaling approximately $440,000, was treated as a deduction from the note proceeds (debt discount) and amortized as interest expense over the period the notes were outstanding. The warrants entitled the note holders to obtain a certain number of preferred shares, based on a specific formula outlined in the agreement, at the issuance price of the qualified preferred stock financing. When the Company completed its Series B redeemable convertible preferred stock ("Series B Preferred") financing in May 2006, the aggregate principal and interest outstanding on the convertible notes of $8,247,000 was converted into approximately 1,084,000 shares of Series B Preferred at the issuance price of $7.6055 per share. In addition, the number and the exercise price of the warrants issued in connection with the bridge financing was established at the time of the issuance of the Series B Preferred, resulting in warrants exercisable for approximately 243,000 shares of Series B Preferred at an exercise price of $7.6055 per share. The Company classified the warrants as a liability and remeasured the liability to estimated fair value at December 31, 2011 using the Black-Scholes option pricing model under the following assumptions: contractual life according to the remaining terms of the warrants, no dividend yield, risk-free interest rate of 0.13% and volatility of 72%.

	The increase in the fair value of the warrants from issuance through IPO in October of 2012, totaled $1,205,000 and has been recorded in warrant and other income (expense), net, and included $349,000 and $265,000 of interest expense in the statements of operations and comprehensive loss for the years ended December 31, 2012 and 2011, respectively. Effective immediately prior to the closing of the Company's IPO in October of 2012, the warrants for convertible preferred stock became warrants for common stock and were reclassified to equity. All but 178 warrants were exercised during 2012, with the remaining warrants being exercised in January 2013, resulting in the net issuance of 153,000 shares of common stock.

Notes_Payable

Notes Payable	12 Months Ended
Notes Payable	Dec. 31, 2013
Notes Payable	'
Notes Payable	'

	5. Notes Payable

	On March 21, 2011, the Company executed a debt financing agreement whereby the Company had access to borrow up to $15,000,000 of senior loan financing through January 1, 2012. On December 30, 2011, the Company amended its credit facility to provide for an extension of its drawdown period through December 1, 2012, provided that it had drawn down at least $5,000,000 as of August 1, 2012. On July 23, 2012, the Company obtained an additional 60 day extension to the initial drawdown date from August 1, 2012 to October 1, 2012. For each draw, the Company shall make six months of interest only payments at a fixed rate of 11.5% followed by 30 months of interest and principal payments at a fixed rate of 8.5% and a final payment of 6% of the amount drawn. The debt is secured by all the Company's assets, except for the Company's intellectual property, which is subject to a negative pledge agreement.

	On October 1, 2012 the Company drew $5,000,000 and in November 2012, obtained an extension allowing for the draw of the remaining $10,000,000 in $5,000,000 increments by January 31, 2013 and February 28, 2013. On January 31, 2013 the Company drew down an additional $5,000,000 of available funds under its credit facility and on February 28, 2013, the Company drew the remaining $5,000,000.

	Upon entry into the agreement, the Company issued warrants to purchase 34,000 shares of Series C redeemable convertible preferred stock ("Series C Preferred") at an exercise price of $13.3530. The estimated fair value of the warrants at issuance of approximately $345,000 was recorded as a deferred financing cost offsetting the notes payable liability and is being amortized to interest expense over the expected term of the loan.

	Upon extension of the credit facility in December 2011, the Company issued a warrant to purchase up to an additional 86,000 shares of its Series D redeemable convertible preferred stock ("Series D Preferred") at an exercise price of $13.9040. The estimated fair value of the warrant at issuance of approximately $1,074,000 was recorded as a deferred financing cost offsetting the notes payable liability and is being amortized to interest expense over the expected term of the loan.

	As of December 31, 2013 and December 31, 2012, $15,000,000 and $5,000,000 respectively had been drawn. There is no further borrowing capacity under this facility as of December 31, 2013.

	Effective immediately prior to the closing of the Company's IPO, the warrants for convertible preferred stock became warrants for common stock. Prior to the IPO, the Company had classified the warrants as a liability and remeasured the liability to estimated fair value using the Black-Scholes option pricing model. Assumptions used to revalue the Series C Preferred warrants at December 31, 2011 were as follows: contractual life according to the remaining terms of the warrants, no dividend yield, risk-free interest rate of 1.75% and volatility of 80%. Assumptions used to revalue the Series D Preferred warrants at December 31, 2011 were as follows: contractual life according to the remaining terms of the warrants, no dividend yield, risk-free interest rate of 1.89% and volatility of 81%. Upon this conversion, the warrants ceased to be remeasured and the warrant liability was reclassified to equity.

	The increase in the fair value of the Series C Preferred warrants from issuance in March 2011 through the IPO in October of 2012, totaled $55,000 and was recorded in warrant and other income (expense), net, in the statement of operations and comprehensive loss, and included expense of $91,000 and income of $36,000 for the years ended December 31, 2012 and 2011, respectively. The decrease in value of the Series D Preferred warrants from issuance in December 2011 through the IPO in October of 2012 totaled $18,000 and was recorded in warrant and other income (expense), net, in the statement of operations and comprehensive loss for the year ended December 31, 2012. There was no change in the fair value of the Series D Preferred warrants during the year ended December 31, 2011 due to the timing of issuance.

	All warrants were exercised on a cashless basis in December of 2012 resulting in the net issuance of 49,000 shares of common stock and there were no warrants outstanding as of December 31, 2012.

	Interest expense on the notes is being recorded over the expected term of the notes in accordance with the effective interest method. Included in interest expense for the years ended December 31, 2013 and 2012 was amortization of debt issuance costs of $340,000 and $272,000 and interest expense of $1,640,000 and $169,000 related to the notes payable, respectively. The balance of accrued interest expense at December 31, 2013 and 2012 was $375,000 and $22,000, respectively. The remaining unamortized debt issuance cost at December 31, 2013 and 2012 was $736,000 and $1,076,000, respectively.

	The credit facility includes various covenants. As of December 31, 2013 and 2012, we were in compliance with all covenants associated with the credit facility.

	Future maturities of the Notes payable as of December 31, 2013 are as follows:


	2014	$	5,866,000
	2015		5,823,000
	2016		552,000


			12,241,000
	Unamortized debt issuance cost		(736,000	)


			11,505,000
	Current portion		(5,526,000	)


	Notes payable—net of current portion	$	5,979,000

Redeemable_Convertible_Preferr

Redeemable Convertible Preferred Stock	12 Months Ended
Redeemable Convertible Preferred Stock	Dec. 31, 2013
Redeemable Convertible Preferred Stock	'
Redeemable Convertible Preferred Stock	'

	6. Redeemable Convertible Preferred Stock

	In August 2011, the Company issued 2,692,000 shares of its Series D Preferred at a price of $13.9040 per share, for aggregate gross proceeds of $37,425,000.

	Upon IPO in October of 2012, all shares of convertible preferred stock converted into 11,545,000 shares of common stock. The Series A Preferred, Series C Preferred and Series D Preferred were converted into common stock on a 1-for-1 basis. The Series B Preferred was converted into shares of common stock on a 1-for-1.00785 basis.

	Dividends

	The holders of the Preferred Stock were entitled to receive dividends, when and if declared by the board of directors. No dividends had been declared through the date of conversion.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
Stockholders' Equity	Dec. 31, 2013
Stockholders' Equity	'
Stockholders' Equity	'

	7. Stockholders' Equity

	Shares Reserved for Future Issuance

	Shares of the Company's common stock reserved for future issuance are as follows:


			December 31,
			2013			2012
	Common stock awards outstanding			2,335,000			1,956,000
	Common stock awards available for grant			295,000			438,000


	Total common shares reserved for future issuance			2,630,000			2,394,000





	Stock Options

	In September 2012, the Company's board of directors approved the 2012 Equity Incentive Award Plan ("the Plan"), which became effective upon completion of our IPO. The Plan provides for the granting of incentive and nonstatutory stock options, restricted stock, restricted stock units, stock appreciation rights, deferred stock, dividend equivalents, performance awards, stock payments and other stock-based and cash-based awards to its employees, directors, and consultants at the discretion of the compensation committee of the board of directors. The Plan is the successor to the Amended and Restated 2004 Stock Plan. Any remaining shares available for future issuance under the 2004 Stock Plan are available for issuance under the Plan. In addition, the plan reserve will automatically increase annually from January 1, 2013 through January 1, 2022 by an amount equal to the smaller of: (a) 1,512,687 shares, (b) four percent of the number of shares of common stock issued and outstanding on the immediately preceding December 31, or (c) an amount determined by the Company's board of directors. As of December 31, 2013, 2012 and 2011, a total of 3,224,000, 2,491,000 and 2,113,000 shares, respectively, were authorized for grant under the Plan.

	Stock options may be granted with exercise prices not less than the estimated fair value of the Company's common stock. Incentive stock options granted to individuals owning more than 10% of the total combined voting power of all classes of stock are exercisable up to five years from the date of grant. The Plan provides that the exercise price of any incentive stock option granted to a 10% stockholder cannot be less than 110% of the estimated fair value of the common stock on the date of grant. Except as set forth above, options granted under the Plan expire no later than ten years from the date of grant. Options granted to employees under the Plan vest over periods determined by the board of directors, which generally vest over four years. Additionally, the Company has granted certain performance-based stock option awards that vest based on the achievement of certain predetermined milestones. Prior to our IPO, the board of directors determined the estimated fair value of its common stock based on assistance from an independent third-party valuation expert. Since our IPO, the fair value of the Company's common stock is the closing share price as reported on the NASDAQ Global Select Market on the date of grant. The fair value of the Company's common stock was determined to be $37.35, $30.34 and $8.22 at December 31, 2013, 2012 and 2011, respectively.

	A summary of stock award activity for the years ended December 31, 2013, 2012, and 2011 is as follows:


			Number of			Weighted-Average			Weighted-Average		Weighted-Average
			Options			Exercise			Remaining		Intrinsic
						Price			Contractual		Value
									Term (in years)
	Outstanding at December 31, 2010			1,394,000		$	3.6			7.61
	Granted			78,000			7.26			9.59
	Exercised			(12,000	)		1.48				$	5.13
	Forfeited			(25,000	)		5.18


	Outstanding at December 31, 2011			1,435,000		$	3.78			6.76
	Granted			652,000			10.19			9.28
	Exercised			(51,000	)		2.4				$	7.56
	Forfeited			(80,000	)		6.31


	Outstanding at December 31, 2012			1,956,000		$	5.86			6.87
	Granted			978,000			25.9			9.26
	Exercised			(496,000	)		2.75				$	26.1
	Forfeited			(103,000	)		16.35


	Outstanding at December 31, 2013			2,335,000		$	14.45			7.49




	Vested or expected to vest at December 31, 2013			2,271,000		$	14.25			7.45
	Exercisable at December 31, 2013			1,020,000		$	6.75			5.7

	Included in grants made during 2013 were 62,500 restricted stock units, all of which were unvested and outstanding at December 31, 2013 and had a weighted average grant date fair value of $27.16. No restricted stock units were granted prior to 2013. At December 31, 2013, the aggregate intrinsic value of equity awards outstanding, exercisable, and vested or expected to vest was $54,180,000, $31,280,000 and $52,509,000 respectively.

	The Company estimates the fair value of its share-based awards to employees and directors using the Black-Scholes option pricing model. The Black-Scholes model requires the input of complex and subjective assumptions, including (a) the expected stock price volatility, (b) the calculation of expected term of the award, (c) the risk free interest rate and (d) expected dividends. Due to the Company's limited operating history and a lack of company specific historical and implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. When selecting these public companies on which it has based its expected stock price volatility, the Company selected companies with comparable characteristics to it, including enterprise value, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected life of the stock-based awards. The historical volatility data was computed using the daily closing prices for the selected companies' shares during the equivalent period of the calculated expected term of the stock-based awards. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. The Company has estimated the expected life of its employee stock options using the "simplified" method, whereby, the expected life equals the arithmetic average of the vesting term and the original contractual term of the option due to its lack of sufficient historical data. The risk-free interest rates for periods within the expected life of the option are based on the U.S. Treasury yield curve in effect during the period the options were granted. The Company has never paid, and does not expect to pay dividends in the foreseeable future.

The weighted-average assumptions used to estimate the fair value of stock options using the Black-Scholes option pricing model were as follows:


		Year Ended December 31,
		2013			2012			2011
Weighted-average exercise price of options granted		$	25.9		$	10.19		$	7.26
Expected volatility			67	%		75	%		77	%
Expected term (in years)			5.9			6.1			5.8
Weighted-average risk free interest rate			1.28	%		1.05	%		1.55	%
Expected dividends			0	%		0	%		0	%
Weight-average grant date fair value			17.85			7.09			4.83

The Company is also required to estimate forfeitures at the time of grant, and revise those estimates in subsequent periods if actual forfeitures differ from its estimates. The Company uses historical data to estimate pre-vesting option forfeitures and record stock-based compensation expense only for those awards that are expected to vest. To the extent that actual forfeitures differ from the Company's estimates, the difference is recorded as a cumulative adjustment in the period the estimates were revised. For the years ended December 31, 2013, 2012 and 2011, the Company applied a forfeiture rate based on the Company's historical forfeitures. No forfeiture rate was applied prior to January 1, 2011 as forfeitures prior to such date had been insignificant. Total equity-based compensation cost recorded in the statements of operations and comprehensive loss, which includes the value of stock options, restricted stock units, and the value of stock options issued to nonemployees and directors for services is allocated as follows:


		Year Ended December 31,
		2013			2012			2011
Research and development		$	3,869,000		$	904,000		$	451,000
General and administrative			2,634,000			953,000			407,000


		$	6,503,000		$	1,857,000		$	858,000





As of December 31, 2013, there was $13,287,000 of unrecognized compensation expense related to unvested employee stock award agreements, which is expected to be recognized over a weighted-average period of approximately 2.32 years. For stock awards subject to graded vesting, the Company recognizes compensation cost on a straight-line basis over the service period for the entire award.

The Company continues to account for stock options issued to nonemployees using a fair value approach. The compensation costs of these arrangements are subject to remeasurement over the vesting terms as earned.

During the years ended December 31, 2013, 2012 and 2011, the Company granted nonemployees options to purchase approximately 24,000, 16,000 and 19,000 shares of its common stock, respectively, at exercise prices ranging from $43.69 to $6.58 per share. Compensation expense related to nonemployee option grants of $867,000, $250,000 and $50,000 were recorded for the years ended December 31, 2013, 2012 and 2011, respectively.

The fair value of nonemployee options in the years ended December 31, 2013, 2012 and 2011 was estimated using the Black-Scholes option pricing model with the following weighted-average assumptions: no dividend yield, volatility of 60%, 73% and 76%, maximum contractual life of ten years, and a risk-free interest rate of 1.19%, 0.67% and 1.38%.

Commitments_Collaborations_and

Commitments, Collaborations and Contingencies	12 Months Ended
Commitments, Collaborations and Contingencies	Dec. 31, 2013
Commitments, Collaborations and Contingencies	'
Commitments, Collaborations and Contingencies	'

	8. Commitments, Collaborations and Contingencies

	Commitments

	The Company leases its facilities and certain equipment under operating leases.

	In 2011, the Company renegotiated its facility lease through December 31, 2013. The renegotiated lease commenced in June 2011. Additionally, in May 2012, the Company leased additional space at the same facility through April 30, 2014. In March 2013, the Company extended its leases through June 30, 2014 and in January 2014, extended again through July 31, 2014. The future minimum rental payments under these leases are included in the future minimum rental payments below. The lease is subject to fixed rate escalation increases. As a result, the Company recognizes rent expense on a straight-line basis for the full amount of the commitment including the minimum rent increases over the life of the lease. Under the terms of the lease agreements, the Company expects to incur rent expense associated with its office leases through July 31, 2014 of approximately $246,000. Refer to Note 13, "Subsequent Events (unaudited)" for a discussion of lease obligations associated with the new lease entered into in March 2014.

	Rent expense under the Company's operating leases for the years ended December 31, 2013, 2012 and 2011, was $409,000, $379,000 and $265,000, respectively.

	Collaboration Arrangements

	From time to time, the Company enters into collaborative arrangements for its research and development and manufacturing activities. Each collaboration is unique in nature and the Company's significant agreements are discussed below.

	Bayer—See Note 13, "Subsequent Events (unaudited)"

	In August 2010, the Company entered into a license agreement with Bayer Consumer Care AG that provides Bayer with an exclusive license to develop, manufacture and commercialize ATX-101 outside of the United States and Canada. In connection with the License Agreement the Company also entered into a related Services, Research, Development and Collaboration Agreement with Bayer's affiliate, Intendis GmbH. These agreements are referred to jointly as the collaboration arrangement with Bayer, and Bayer Consumer Care AG and Intendis GmbH are referred to jointly as Bayer. In connection with the entry into the collaboration arrangement, Bayer paid the Company an upfront license fee of approximately $21,319,000 and approximately $22,247,000 for research and development to fund a portion of Bayer's European Phase III clinical trials. The Company was eligible to receive up to $297,000,000 for certain development, manufacturing, regulatory and commercialization contingent payments upon the achievement by Bayer of specified events under our collaborative arrangement, as well as escalating royalties from the mid- to high-teens on Bayer's net product sales of ATX-101. The first of these contingent event-based payments of $15,800,000 was received on May 31, 2012, triggered by the completion of Bayer's European Phase III clinical trial for ATX-101, the receipt of two consecutive validated manufacturing lots and Bayer's subsequent decision to pursue continued development and seek regulatory approval of ATX-101. This amount was recorded as revenue upon receipt as all revenue recognition criteria had been met. At this time, Bayer also elected to pursue additional research and development activities related to ATX-101, which are distinct from the original development activities, and subsequently funded $17,400,000 for these additional Bayer development activities. This payment was recorded as restricted cash and deferred development funds and will be recognized as an offset to development expense as the restricted cash is utilized to fund Bayer's development activities.

	Bayer had the right to terminate the license agreement at any time upon advance notice of 180 days if Bayer determined that ATX-101 did not appear to be commercially viable or if there was a material change in circumstances that impacted the prospective profitability of ATX-101. The license agreement expired simultaneously with the expiration of royalties on a product-by-product/country-by-country basis, and expired in its entirety upon the expiration of royalties with respect to all products outside of the United States and Canada. Such royalties expired on the later of (i) the expiration of patent claims relating to ATX-101, (ii) the expiration of exclusivity extensions for ATX-101, or (iii) 15 years from the date of first commercial sale, each with respect to the relevant country. The royalty payments discussed above were subject to reduction in connection with, among other things, the entry into the market of certain products competitive to ATX-101. In the event a competitive product meeting certain qualifications was approved for sale and was actually and legally sold in a particular territory (in the case of the EU, any member country), the Company's royalties on Bayer's net sales of ATX-101 in that territory would have been reduced from the mid- to high-teens to the low-single digits to low-teens depending upon the timing and territory of such competitive entry. Except with respect to the EU, the entry of a qualifying competitive product into one territory would not have resulted in a reduction in the royalty payments applicable to Bayer's net sales in other territories. Similarly, our royalties on Bayer's net sales of ATX-101 would have been reduced to the low- to mid-single digits, or eliminated entirely, in each country in which an approved generic was actually and legally sold in such country, depending on the timing and country of such generic entry. The license agreement may also have been terminated by us upon Bayer commencing an action that challenged the validity of ATX-101-related patents or if Bayer ceased or abandoned developing ATX-101 outside of the United States and Canada. The license agreement may also have been terminated by either party in the event of a material breach by the other party.

	License fees of $21,319,000 were deferred and recognized on a straight-line basis over the period of substantial involvement in collaboration activities that were required to be conducted relative to the upfront license fee and development funds received from Bayer. These activities were completed as of May 31, 2012.

	Amounts to fund collaboration efforts of $22,247,000 and $17,400,000 were recorded as restricted cash and deferred development funds and recognized as an offset to research and development expenses as the restricted cash was utilized to fund development activities. Restricted cash and deferred development funds presented as current and long-term on the balance sheet are based on the Company's estimate of amounts that will be spent to fund development activities within the next 12 months. Amounts recognized as offsets to research and development expense were $11,739,000, $10,075,000 and $14,615,000 for the years ended December 31, 2013, 2012 and 2011, respectively. Additionally at December 31, 2013 and 2012 we had accrued $2,395,000 and $1,762,000 of costs related to services performed in accordance with the collaboration agreement and to be paid with deferred development funds.

	Los Angeles Biomedical Research

	In August 2005, the Company entered into an exclusive license agreement with Los Angeles Biomedical Research Institute at Harbor/UCLA Medical Center, or LA Biomed, pursuant to which it obtained a worldwide exclusive license to practice, enforce and otherwise exploit certain patent rights related to the use of the active ingredient in ATX-101. The exclusive license requires the Company to pay LA Biomed a milestone payment of $500,000 upon receipt of marketing approval of ATX-101, as well as non-royalty sublicense fees equal to 10% of any sublicense income, up to a total of $5,000,000, 50% of which the Company may elect to satisfy through the issuance of capital stock. Additionally, upon commercialization of a licensed product or service, the Company is obligated to pay low- to mid- single digit royalties on net product sales of ATX-101. The Company may terminate this license without penalty upon 90 days' notice to LA Biomed and LA Biomed may terminate the license in certain circumstances if the Company fails to perform, or violates any term of the agreement, subject to applicable cure provisions. Subject to default by the Company or termination, the license remains in effect until the last patent or patent application in the licensed patent rights has expired or been revoked, invalidated or abandoned.

	In August 2010, due to the receipt of the upfront license fee from Bayer, the Company incurred non-royalty sublicense fees of $1,950,000, which was deferred and recognized as sublicense fee expense on a straight-line basis over the same period as the license income. During 2010, the Company made payments of cash and stock to LA Biomed totaling $390,000 related to the non-royalty sublicense fee incurred. The remainder of $1,560,000 was paid upon our IPO in 50% cash and 50% stock.

	Additionally, due to the receipt of the contingent event-based payment of $15,800,000 payable from Bayer on May 31, 2012, the Company incurred an additional non-royalty sublicense fee of $1,580,000 to LA Biomed, which was paid in 50% cash and 50% stock.

	Supply Arrangements

	Pfizer, Inc.

	The Company currently has an exclusive supply agreement with Pfizer, Inc., or Pfizer, as the single-source supplier of a key raw material for ATX-101. The agreement with Pfizer expires in December 2014. The agreement can also be terminated prior to expiration by either party (i) upon 60 days' written notice of an uncured material breach, (ii) upon 24 months' written notice, (ii) the bankruptcy or insolvency of the other party or (iv) by Pfizer if the Company abandons development of ATX-101. The Company is not required to purchase any minimum or specific quantities from Pfizer, however, any purchase of the key starting material must be made from Pfizer. Payments are due to Pfizer 30 days after receipt of an invoice following shipment of the material.

	Hospira, Inc.

	In November 2010, the Company entered into a long-term agreement with Hospira, Inc., or Hospira, as its drug product fill/finish supplier. The initial term of the agreement expires five years after the first day of the month after our first bona fide sale of ATX-101 to a non-affiliate customer after ATX-101 receives regulatory approval, and may be extended for additional and successive two year terms. The agreement may be terminated prior to expiration by either party upon 24 months' written notice. The agreement may also be terminated by either party upon 60 days' written notice of an uncured material breach, the bankruptcy or insolvency of the other party or upon notice that the other party is unable to perform for 180 days due to a force majeure. The Company is not required to purchase any minimum or specific quantities from Hospira; however, if ATX-101 is approved, Hospira has the right to be the Company's sole provider of drug product for a period of three year following commercialization, and, following the completion of the third year, the right to provide no less than seventy-five percent of the Company's total annual requirement of drug product. Payments are due to Hospira 30 days after receipt of an invoice or, with respect to certain pre-specified events, upon completion of such event.

	Contingencies

	From time to time, the Company may be subject to various litigation and related matters arising in the ordinary course of business. The Company is currently not subject to any such matters where there is at least a reasonable possibility that a material loss may have been incurred.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2013
Fair Value Measurements	'
Fair Value Measurements	'

	9. Fair Value Measurements

	The Company applies various valuation approaches in determining the fair value of its financial assets and liabilities within a hierarchy that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company's assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances. The fair value hierarchy is broken down into three levels based on the source of inputs as follows:

	Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access.

	Level 2—Valuations based on quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active and models for which all significant inputs are observable, either directly or indirectly.

	Level 3—Valuations based on inputs that are unobservable and significant to the overall fair value measurement.

	The availability of observable inputs can vary among the various types of financial assets and liabilities. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, for financial statement disclosure purposes, the level in the fair value hierarchy within which the fair value measurement is categorized is based on the lowest level input that is significant to the overall fair value measurement.

	At December 31, 2013 and 2012, the Company had cash equivalents comprised of U.S. Treasury securities money market accounts whose value is based using quoted market prices with no adjustments applied. Accordingly, these securities are classified as Level 1. U.S. Government agency securities and corporate debt securities are measured at fair value using Level 2 inputs. These securities are investment grade with maturity dates of two years or less from the balance sheet date. The Company reviews trading activity and pricing for these investments as of the measurement date. When sufficient quoted pricing for identical securities is not available, the Company uses market pricing and other observable market inputs for similar securities obtained from various third party data providers. These inputs represent quoted prices for similar assets in active markets or these inputs have been derived from observable market data. This approach results in the classification of these securities as Level 2 of the fair value hierarchy. The Company had no assets or liabilities classified as Level 3. There were no material remeasurements to fair value during the years ended December 31, 2013, 2012 and 2011, of financial assets and liabilities that are not measured at fair value on a recurring basis. There were no transfers of assets or liabilities between the fair value measurement levels during the years ended December 31, 2013 and 2012.

	The following fair value hierarchy table presents information about each major category of the Company's financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2013 and 2012.


		Fair Value Measurement at December 31, 2013 Using:
		Quoted Prices		Significant		Significant		Balance as of
		in Active		Other		Unobservable		December 31, 2013
		Markets for		Observable		Inputs
		Identical		Inputs		(Level 3)
		Assets		(Level 2)
		(Level 1)
	Assets
	Cash equivalents	$	95,537,000	$	—	$	—	$	95,537,000
	U.S. government agency securities		—		2,003,000		—		2,003,000
	Corporate debt securities		—		53,537,000		—		53,537,000


	Total	$	95,537,000	$	55,540,000	$	—	$	151,077,000









		Fair Value Measurement at December 31, 2012 Using:
		Quoted Prices		Significant		Significant		Balance as of
		in Active		Other		Unobservable		December 31, 2012
		Markets for		Observable		Inputs
		Identical		Inputs		(Level 3)
		Assets		(Level 2)
		(Level 1)
	Assets:
	Cash equivalents	$	71,316,000	$	—	$	—	$	71,316,000


	Total	$	71,316,000	$	—	$	—	$	71,316,000





	The fair values of cash equivalents, accounts payable and accrued liabilities approximate their carrying values due to the short-term nature of these accounts. Based on the borrowing rates currently available to the Company for debt with similar terms and consideration of default and credit risk, the carrying value of the notes payable approximates their fair value.

401k_Savings_Plan

401(k) Savings Plan	12 Months Ended
401(k) Savings Plan	Dec. 31, 2013
401(k) Savings Plan	'
401(k) Savings Plan	'

	10. 401(k) Savings Plan

	In 2006, the Company sponsored a defined contribution savings plan under Section 401(k) of the Internal Revenue Code ("the 401(k) Plan"). The 401(k) Plan covers all employees who meet defined minimum age and service requirements, and allows participants to defer a portion of their annual compensation on a pretax basis. The Company matches a percentage of its eligible employees' contributions. For the years ended December 31, 2013, 2012 and 2011, the total amounts included in expense for its contributions were $341,000, $208,000 and $156,000, respectively.

Income_Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2013
Income Taxes	'
Income Taxes	'

	11. Income Taxes

	There is no provision for income taxes because the Company has incurred operating losses since inception. At December 31, 2013, the Company has concluded that it is more likely than not that the Company may not realize the benefit of its deferred tax assets due to its history of losses. Accordingly, the net deferred tax assets have been fully reserved.

	The Company recorded deferred tax assets of approximately $73,687,000 and $49,447,000 as of December 31, 2013 and 2012, respectively, which have been fully offset by a valuation allowance due to uncertainties surrounding its ability to generate future taxable income to realize these assets. The deferred tax assets are primarily composed of federal and state tax net operating loss, or NOL carryforwards, start-up expenditures and R&D credit carryforwards. As of December 31, 2013, the Company has federal NOL carryforwards of approximately $152,000,000, which will expire at various times through 2033. Of these deferred tax assets, approximately $7,450,000 will be credited directly to additional paid in capital. At December 31, 2013, the Company has federal and state tax credit carryforwards of approximately $7,200,000 and $4,500,000 available to reduce future federal and state tax liability, respectively. The federal tax credits begin to expire in 2026. Under California law, California tax credits do not have an expiration date.

	In general, if the Company experiences a greater than 50 percentage point aggregate change in ownership of certain significant stockholders over a three-year period (a "Section 382 ownership change"), utilization of its pre-change NOL carryforwards are subject to an annual limitation under Section 382 of the Internal Revenue Code (and similar state laws). The annual limitation generally is determined by multiplying the value of the Company's stock at the time of such ownership change (subject to certain adjustments) by the applicable long-term tax-exempt rate. Such limitations may result in expiration of a portion of the NOL carryforwards before utilization and may be substantial. The Company has determined that ownership changes have occurred in prior years which, after limitations, will likely result in approximately $800,000 of its NOL carryforwards expiring unutilized. Accordingly, the related deferred tax assets and corresponding valuation allowance have been removed from the components of deferred tax assets. The ability of the Company to use its remaining NOL carryforwards may be further limited or lost if the Company experiences additional Section 382 ownership changes as a result of future changes in its stock ownership.

	The components of deferred tax assets at December 31, 2013 and 2012 are as follows:


			December 31,
			2013			2012
	Net operating losses		$	57,010,000		$	38,131,000
	Research & development credits			8,652,000			4,771,000
	Start-up expenditures			5,214,000			5,661,000
	Stock compensation			2,447,000			518,000
	Depreciation			204,000			237,000
	Accruals			160,000			129,000
	Valuation allowance			(73,687,000	)		(49,447,000	)


	Total deferred income taxes		$	—		$	—





	The components of the net income tax benefit for the years ended December 31, 2013, 2012 and 2011 are as follows:


			2013			2012			2011
	Benefit for income taxes
	Current		$	—		$	—		$	—
	Deferred			24,240,000			14,913,000			4,840,000
	Valuation allowance			(24,240,000	)		(14,913,000	)		(4,840,000	)


	Net income tax benefit		$	—		$	—		$	—





	A reconciliation of the difference between the benefit for income taxes and income taxes at the statutory U.S. federal income tax rate is as follows for the years ended December 31, 2013, 2012 and 2011:


			2013			2012			2011
	Income tax benefit at statutory rate		$	17,650,000		$	12,512,000		$	3,791,000
	State income taxes, net of federal benefit			2,918,000			1,980,000			595,000
	Research & development credits			1,839,000			542,000			2,926,000
	Return to provision adjustments			2,022,000			475,000			(36,000	)
	Permanent items			(189,000	)		(596,000	)		(324,000	)
	Federal benefit of prior year state deferred items			—			—			(2,112,000	)
	Valuation allowance			(24,240,000	)		(14,913,000	)		(4,840,000	)


	Net benefit		$	—		$	—		$	—





The reconciliation of the total gross amounts of unrecognized tax benefits "UTBs" (excluding interest, penalties, and the federal tax benefit of state taxes related to UTBs) for the years ended December 31, 2013, 2012 and 2011, is as follows:


		2013			2012			2011
Balance at beginning of year		$	842,000		$	655,000		$	—
Additions based on tax positions related to current year			685,000			187,000			655,000
Reductions for tax positions of prior years			—			—			—
Settlements			—			—			—


Balance at end of year		$	1,527,000		$	842,000		$	655,000





If all of the UTBs were recognized, it would not impact the Company's effective tax rate because likely corresponding adjustments to deferred tax assets would be offset to recorded valuation allowances.

The Company's policy is to recognize interest expense and penalties related to income tax matters as a component of income tax expense. There was no accrued interest and penalties associated with uncertain tax positions as of December 31, 2013, 2012 and 2011.

Selected_Quarterly_Financial_D

Selected Quarterly Financial Data (unaudited)	12 Months Ended
Selected Quarterly Financial Data (unaudited)	Dec. 31, 2013
Selected Quarterly Financial Data (unaudited)	'
Selected Quarterly Financial Data (unaudited)	'

	12. Selected Quarterly Financial Data (unaudited)

	The following table contains quarterly financial information for 2013 and 2012. The Company believes that the following information reflects all normal recurring adjustments necessary for a fair statement of the information for the periods presented. The operating results for any quarter are not necessarily indicative of results for any future period.


		First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	Year Ended December 31, 2013
	License income, net	$	—		$	—		$	—		$	—
	Total operating expenses		13,759,000			11,740,000			11,004,000			13,563,000
	Other income (expense), net		(367,000	)		(518,000	)		(505,000	)		(455,000	)
	Net loss		(14,126,000	)		(12,258,000	)		(11,509,000	)		(14,018,000	)
	Net loss per share, basic and diluted	$	(0.77	)	$	(0.67	)	$	(0.62	)	$	(0.66	)





		First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	Year Ended December 31, 2012
	License income, net	$	1,748,000		$	16,003,000		$	—		$	—
	Total operating expenses		8,680,000			10,868,000			16,362,000			17,779,000
	Other income (expense), net		49,000			(629,000	)		(24,000	)		(257,000	)
	Net (loss) income		(6,883,000	)		4,506,000			(16,386,000	)		(18,036,000	)
	Net (loss) income per share, basic	$	(4.91	)	$	3.17		$	(11.41	)	$	(1.18	)
	Net (loss) income per share, diluted	$	(4.91	)	$	0.32		$	(11.41	)	$	(1.18	)

Subsequent_Events_unaudited

Subsequent Events (unaudited)	12 Months Ended
Subsequent Events (unaudited)	Dec. 31, 2013
Subsequent Events	'
Subsequent Events	'

	13. Subsequent Events (unaudited)

	On March 12, 2014, the Company entered into a facility lease agreement for 24,475 square feet of office space in Westlake Village, CA with a monthly base rent of $62,000 subject to annual fixed rate escalation increases of 3% for a term of 36 months beginning on August 1, 2014 with an option to renew for an additional 36 months. The lease includes an additional 8,723 square feet commencing no later than April 1, 2015 at the same rate per square foot. The total commitment associated with the initial 36 month term lease is approximately $3,000,000.

	In March 2014, the Company entered into an agreement whereby it acquired the rights to develop and commercialize ATX-101 outside of the United States and Canada from Bayer in exchange for consideration of $84,000,000, comprised of $33,000,000 in KYTHERA common stock based on a stock price of the average of 10 trading days before and after the transaction and a $51,000,000 unsecured promissory note. The promissory note, which is subordinated to amounts owed under our existing credit facility, bears interest at 5% per annum and is payable no later than 2024. Additionally, Bayer is eligible to receive up to $123,800,000 upon the achievement of certain long-term sales milestone payments on annual sales of ATX-101 outside of the United States and Canada.

	The Company is in the process of completing its accounting for the acquisition of these rights. Based on the Company's analysis to date, it believes that the transaction should be accounted for as an acquisition of a group of assets. Since the acquired rights represent acquired in-process research and development with no alternative future uses, the Company expects to incur a material charge in the quarter ending March 31, 2014 as a result of expensing the resulting value assigned to such rights.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2013
Summary of Significant Accounting Policies	'
Basis of Presentation	'

	Basis of Presentation

	The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP.

Reclassifications	'

	Reclassifications

	Certain prior year amounts have been reclassified to conform to the current year presentation.

Use of Estimates	'

	Use of Estimates

	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the financial statements and accompanying notes. Actual results could materially differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including: expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. 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. This process may result in actual results differing materially from those estimated amounts used in the preparation of the financial statements.

Segment Reporting	'

	Segment Reporting

	To date, the Company has viewed its operations and manages its business as one segment operating primarily in the United States.

Cash and Cash Equivalents and Marketable Securities	'

	Cash and Cash Equivalents and Marketable Securities

	All highly liquid securities with maturities of 90 days or less from the date of purchase are considered to be cash equivalents. As of December 31, 2013 and 2012, cash and cash equivalents are comprised of funds invested in cash and money market accounts. The Company maintains cash balances in excess of amounts insured by the Federal Deposit Insurance Corporation, or FDIC. The accounts are monitored by management to mitigate the risk.

	Investments with maturities of more than 90 days from the date of purchase are considered marketable securities. Marketable securities are stated at fair value. The Company has classified the entire marketable securities portfolio as available-for-sale securities. Accordingly, any unrealized gain or loss on the investments is reported as a component of accumulated other comprehensive income (loss). The amortized cost of these securities is adjusted for amortization of premiums and accretion of discounts to maturity, as applicable. Such amortizations and accretions are included in interest income. The entire marketable securities portfolio is considered available for use in current operations and, accordingly, all such investments are considered current assets although the stated maturity of individual investments may be one year or more beyond the balance sheet date.

	Realized gains and losses on sales of marketable securities are determined on a specific identification basis and reported in interest income. When securities are sold, any associated unrealized gain or loss previously reported in accumulated other comprehensive income (loss) is reclassified out of stockholders' equity and recorded in the statement of operations and comprehensive loss for the period. Accrued interest and dividends are included in interest income.

	On a quarterly basis, the Company reviews its available-for-sale securities for other-than temporary declines in fair value below the amortized cost basis. This evaluation is based on a number of factors including the length of time and extent to which the fair value has been below the cost basis and any adverse conditions related specifically to the security, including any changes to the credit rating of the security. If the Company concludes that an other-than- temporary impairment exists, it recognizes an impairment charge to reduce the investment to fair value and records the related charge as a reduction of interest income. No impairment charges were recognized during the year ended December 31, 2013.

	As of December 31, 2012 and 2011, the Company did not have any marketable securities. There were no realized gains or losses from the sale of marketable securities for the years ended December 31, 2012 or 2011 and were immaterial for the year ended December 31, 2013.

Restricted Cash	'

	Restricted Cash

	Restricted cash of $5,602,000 and $15,978,000 at December 31, 2013 and 2012, respectively, represents restricted cash received through the collaboration arrangement with Bayer that will be used to fund certain further global development activities of ATX-101. See Note 8, "Commitments, Collaborations and Contingencies."

	Payments the Company received to fund collaboration efforts under the terms of the collaboration agreement with Bayer were recorded as restricted cash and deferred development funds, and are recognized as an offset to development expenses as the restricted cash is utilized to fund such development activities.

Property and Equipment	'

	Property and Equipment

	Property and equipment are recorded at historical cost and consisted of the following:


		December 31,
		2013			2012
	Cameras	$	923,000		$	923,000
	Computer hardware and electronics		182,000			147,000
	Furniture and fixtures		234,000			227,000
	Software		21,000			21,000


			1,360,000			1,318,000
	Less accumulated depreciation		(1,266,000	)		(1,043,000	)


		$	94,000		$	275,000





	Depreciation is recorded using the straight-line method over the estimated useful lives of the assets (one to five years). The Company reviews its property and equipment assets for impairment in value whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The Company disposed of $54,000 of computer hardware and electronics for the year ended December 31, 2011, with a recognized loss at disposal of $4,000. No disposals were made during the years ended December 31, 2013 and 2012 and no loss on disposal was recognized during the years ended December 31, 2013 and 2012.

	Cameras were used in our clinical trials, are fully depreciated as of December 31, 2013 and are being held for disposal.

Concentration of Credit Risk	'

	Concentration of Credit Risk

	Financial instruments, which potentially subject the Company to significant concentrations of credit risk, consist primarily of cash and cash equivalents and marketable securities. The primary objectives for the Company's investment portfolio are the preservation of capital and the maintenance of liquidity. We do not enter into any investment transaction for trading or speculative purposes.

	The Company's investment policy limits investments to certain types of instruments such as certificates of deposit, money market instruments, obligations issued by U.S. government and U.S. government agencies and corporate debt securities and places restrictions on maturities and concentration by type and issuer. The Company maintains cash balances in excess of amounts insured by the FDIC. The accounts are monitored by management to mitigate the risk.

Stock-Based Compensation	'

	Stock-Based Compensation

	The Company accounts for all stock-based payments issued to employees and directors using an option pricing model for estimating fair value. Accordingly, stock-based compensation expense is measured based on the estimated fair value of the awards on the date of grant, net of forfeitures. Compensation expense is recognized for the portion that is ultimately expected to vest over the period during which the recipient renders the required services to the Company using the straight-line single option method.

	In accordance with authoritative guidance, the fair value of non-employee stock based awards is remeasured as the awards vest, and the resulting increase in fair value, if any, is recognized as expense in the period the related services are rendered.

Redeemable Convertible Preferred Stock Warrants	'

	Redeemable Convertible Preferred Stock Warrants

	Prior to the Company's IPO, freestanding warrants that related to the purchase of redeemable convertible preferred stock were classified as liabilities and recorded at fair value each reporting period regardless of the timing of the redemption feature or the redemption price or the likelihood of redemption. The warrants were subject to remeasurement at each balance sheet date and any change in fair value was recognized as a component of warrant and other income (expense), net. Pursuant to the terms of these warrants, upon the conversion of the class of preferred stock underlying the warrant, the warrants automatically became exercisable for shares of the Company's common stock based upon the conversion ratio of the underlying class of preferred stock. The consummation of the Company's IPO resulted in the conversion of all classes of the Company's preferred stock into common stock. Upon such conversion of the underlying classes of preferred stock, the warrants were reclassified as a component of equity and were no longer subject to remeasurement.

Fair Value of Financial Instruments	'

	Fair Value of Financial Instruments

	The carrying amounts reported in the accompanying financial statements for accounts payable and accrued liabilities approximate their fair value because of the short-term nature of these accounts. The fair value of cash equivalents, marketable securities and the notes payable are discussed in Note 9, "Fair Value Measurements."

Revenue Recognition	'

	Revenue Recognition

	The Company recognizes revenue when all of the following four criteria are present: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; the fee is fixed or determinable; and collectability is reasonably assured.

	For arrangements that involve the delivery of more than one element, each product, service and/or right to use assets is evaluated to determine whether it qualifies as a separate unit of accounting. This determination is based on whether the deliverable has "stand-alone value" to the customer. The consideration that is fixed or determinable is then allocated to each separate unit of accounting based on the relative selling price of each deliverable. The estimated selling price of each deliverable is determined using the following hierarchy of values: (i) vendor-specific objective evidence of fair value, (ii) third-party evidence of selling price (TPE) and (iii) best estimate of selling price (BESP). The BESP reflects our best estimate of what the selling price would be if the deliverable was regularly sold by us on a stand-alone basis. In most cases we expect to use TPE or BESP for allocating consideration to each deliverable. The consideration allocated to each unit of accounting is recognized as the related goods or services are delivered, limited to the consideration that is not contingent upon future deliverables. Analyzing the arrangement to identify deliverables requires the use of judgment, and each deliverable may be an obligation to deliver services, a right or license to use an asset, or another performance obligation.

	The Company's revenue is related to the license agreement with Bayer executed in 2010. This agreement provided for various types of payments, including non-refundable upfront license fees, milestone payments, and future royalties on Bayer's net product sales of ATX-101.

	The Company received a non-refundable upfront license payment of approximately $21,319,000 from Bayer upon execution of the license agreement. The terms of the collaboration arrangement with Bayer included continuing performance obligations and development and clinical manufacturing supply obligations that were conditions to Bayer's decision to pursue continued development and regulatory approval for ATX-101. Due to these ongoing performance obligations, the Company determined that the license did not have stand-alone value. The Company also did not have objective and reliable evidence of the fair value of these undelivered obligations. Accordingly, amounts received upfront under the license agreement were recorded as deferred revenue and were recognized on a straight-line basis over the expected period of substantial involvement in these collaboration activities, which were completed as of May 31, 2012. The period over which these activities were to be performed was based upon management's estimate of the period to complete the development activities required to be conducted relative to the upfront license fee and development funds received from Bayer.

	The Company recognizes revenue from milestone payments when earned, provided that (i) the milestone event is substantive in that it can only be achieved based in whole or in part on either the entity's performance or on the occurrence of a specific outcome resulting from the entity's performance and its achievability was not reasonably assured at the inception of the collaboration arrangement and (ii) the Company does not have ongoing performance obligations related to the achievement of the milestone earned and (iii) it would result in additional payments being due to the Company. Milestone payments are considered substantive if all of the following conditions are met: the milestone payment is non-refundable; achievement of the milestone was not reasonably assured at the inception of the arrangement; substantive effort is involved to achieve the milestone; and the amount of the milestone appears reasonable in relation to the effort expended, the other milestones in the arrangement and the related risk associated with the achievement of the milestone. Any amounts received under the collaboration arrangement in advance of performance, if deemed substantive, are recorded as deferred revenue and recognized as revenue as the Company completes its performance obligations.

Research and Development Costs	'

	Research and Development Costs

	Major components of research and development (R&D) costs include cash compensation, stock-based compensation, pre-clinical studies, clinical trials and related clinical manufacturing, materials and supplies, and fees paid to consultants and other entities that conduct certain research and development activities on the Company's behalf. R&D costs, including upfront fees and milestones paid to collaborators, are expensed as goods are received or services rendered. Costs to acquire technologies to be used in research and development that have not reached technological feasibility and have no alternative future use are also expensed as incurred. Costs incurred in connection with clinical trial activities for which the underlying nature of the activities themselves do not directly relate to active research and development, such as costs incurred for market research and focus groups linked to clinical strategy as well as costs to build the Company's brand, are not included in R&D costs but are reflected as general and administrative expenses.

	The Company enters into agreements with various research institutions, contract laboratories, contract manufacturers and consultants. These agreements are generally on a fee-for-service basis and are cancelable.

Clinical Trial Accruals	'

	Clinical Trial Accruals

	As part of the process of preparing its financial statements, the Company is required to estimate its expenses resulting from its obligations under contracts with vendors and consultants and clinical site agreements in connection with conducting clinical trials. The financial terms of these contracts are subject to negotiations which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to us under such contracts. 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 expended. The Company accounts for these expenses according to the progress of the trial as measured by patient progression and the timing of various aspects of the trial. The Company determines accrual estimates through financial models taking into account discussion with applicable personnel and outside service providers as to the progress or state of consummation of trials, or the services completed. During the course of a clinical trial, the Company adjusts its rate of clinical expense recognition if actual results differ from its estimates. The Company makes estimates of its accrued expenses as of each balance sheet date in its financial statements based on the facts and circumstances known to us at that time. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in us reporting amounts that are too high or too low for any particular period. Through December 31, 2013, there have been no material adjustments to the Company's prior period estimates of accrued expenses for clinical trials. The Company's clinical trial accrual is dependent in part upon the timely and accurate reporting of contract research organizations and other third-party vendors.

Basic and Diluted Net Loss Per Common Share	'

	Basic and Diluted Net Loss Per Common Share

	Basic net loss per common share is computed by dividing the net loss by the weighted average number of common shares outstanding during the period, excluding the dilutive effects of converting redeemable preferred stock, warrants to purchase redeemable convertible preferred stock or common stock and options outstanding. Diluted net loss per common share is computed by dividing the net loss by the sum of the weighted average number of common shares outstanding during the period plus the potential dilutive effects of redeemable convertible preferred stock, warrants to purchase redeemable convertible preferred stock or common stock and options outstanding during the period calculated in accordance with the treasury stock method. Because the impact of these items is anti-dilutive during periods of net loss, there was no difference between the weighted average number of shares used to calculate basic and diluted net loss per common share for the years ended December 31, 2013, 2012 and 2011. The calculation of weighted average diluted shares outstanding excludes the dilutive effect of redeemable convertible preferred stock, warrants to purchase redeemable convertible preferred stock and options to purchase common stock, as the impact of such items are anti-dilutive during periods of net loss. Shares excluded from the calculation, prior to the use of the treasury stock method, unweighted, were 2,335,000, 1,956,000 and 13,334,000 at December 31, 2013, 2012 and 2011, respectively.

Income Taxes	'

	Income Taxes

	The Company accounts for income taxes under the asset and liability method, which requires, among other things, that deferred income taxes be provided for temporary differences between the tax bases of the Company's assets and liabilities and their financial statement reported amounts. A valuation allowance is recorded when it is more likely than not that some portion or all of a deferred tax asset will not be realized. Management has considered estimated future taxable income and ongoing prudent and feasible tax planning strategies in assessing the amount of the valuation allowance. When the Company establishes or reduces the valuation allowance against its deferred tax assets, its provision for income taxes will increase or decrease, respectively, in the period such determination is made.

	Additionally, the Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities based on the technical merits of the position. The tax benefit recognized in the financial statements for a particular tax position is based on the largest benefit that is more likely than not to be realized upon settlement. Accordingly, the Company establishes reserves for uncertain tax positions.

Comprehensive Income (Loss)	'

	Comprehensive Income (Loss)

	Comprehensive income (loss) is comprised of net loss and other comprehensive income (loss). For the year ended December 31, 2013, the only component of other comprehensive income (loss) relates to net unrealized gains and losses on marketable securities. We had no other comprehensive income (loss) for the years ended December 31, 2012 and 2011.

	Effective January 1, 2013, we adopted a new accounting standard that requires increased disclosure regarding amounts that are reclassified out of accumulated other comprehensive income subsequent to January 1, 2013. There were no reclassifications out of accumulated other comprehensive income during the year ended December 31, 2013.

Collaboration Arrangements	'

	Collaboration Arrangements

	From time to time, we enter into certain collaboration arrangements with third parties regarding the research and development, manufacture and/or commercialization of products and product candidates. These collaborations generally provide for non-refundable, upfront license fees, research and development and commercial performance milestone payments, cost sharing and royalty payments. The collaboration agreements with third parties are performed on a "best efforts" basis with no guarantee of either technological or commercial success. The Company evaluates whether an arrangement is a collaboration arrangement at its inception based on the facts and circumstances specific to the arrangement. The Company reevaluates whether an arrangement qualifies or continues to qualify as a collaboration arrangement whenever there is a change in the anticipated or actual ultimate commercial success of the endeavor. See Note 8, "Commitments, Collaborations and Contingencies."

Recent Accounting Pronouncements	'

	Recent Accounting Pronouncements

	In July 2013, a new accounting standard was issued that requires companies to present in the financial statements an unrecognized tax benefit as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward. To the extent the tax benefit is not available at the reporting date under the governing tax law or if the entity does not intend to use the deferred tax asset for such purpose, the unrecognized tax benefit should be presented as a liability and not combined with deferred tax assets. The standard is required to be adopted prospectively beginning on January 1, 2014 and may be applied retrospectively to each prior reporting period presented. The Company does not believe the adoption of this accounting standard will have a material impact on the Company's financial statements and related disclosures.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
Summary of Significant Accounting Policies (Tables)	Dec. 31, 2013
Summary of Significant Accounting Policies	'
Schedule of property and equipment recorded at historical cost	'






		December 31,
		2013			2012
	Cameras	$	923,000		$	923,000
	Computer hardware and electronics		182,000			147,000
	Furniture and fixtures		234,000			227,000
	Software		21,000			21,000


			1,360,000			1,318,000
	Less accumulated depreciation		(1,266,000	)		(1,043,000	)


		$	94,000		$	275,000

Marketable_Securities_Tables

Marketable Securities (Tables)	12 Months Ended
Marketable Securities (Tables)	Dec. 31, 2013
Marketable Securities	'
Schedule of marketable securities held	'

	Our marketable securities held as of December 31, 2013 are summarized below:


		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair Value
				Gains		Losses
	U.S. government agency securities	$	2,000,000	$	3,000	$	—		$	2,003,000
	Corporate debt securities:
	Financial		33,192,000		13,000		(5,000	)		33,200,000
	Industrial		11,081,000		2,000		(3,000	)		11,080,000
	Other		9,263,000		—		(6,000	)		9,257,000


	Total available-for-sale securities	$	55,536,000	$	18,000	$	(14,000	)	$	55,540,000




Schedule of maturities of the entity's marketable securities available for sale	'

	The maturities of our marketable securities available-for-sale as of December 31, 2013 are as follows:


		Amortized		Estimated
		Cost		Fair Value
	Mature in one year or less	$	33,279,000	$	33,293,000
	Mature after one year through two years		22,257,000		22,247,000


		$	55,536,000	$	55,540,000

Notes_Payable_Tables

Notes Payable (Tables)	12 Months Ended
Notes Payable (Tables)	Dec. 31, 2013
Notes Payable	'
Schedule of future maturities of the Notes payable	'

	Future maturities of the Notes payable as of December 31, 2013 are as follows:


	2014	$	5,866,000
	2015		5,823,000
	2016		552,000


			12,241,000
	Unamortized debt issuance cost		(736,000	)


			11,505,000
	Current portion		(5,526,000	)


	Notes payable—net of current portion	$	5,979,000

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	12 Months Ended
Stockholders' Equity (Tables)	Dec. 31, 2013
Stockholders' Equity	'
Schedule of shares of the Company's common stock reserved for future issuance	'






		December 31,
		2013			2012
	Common stock awards outstanding		2,335,000			1,956,000
	Common stock awards available for grant		295,000			438,000


	Total common shares reserved for future issuance		2,630,000			2,394,000




Summary of stock awards activity	'






		Number of			Weighted-Average			Weighted-Average			Weighted-Average
		Options			Exercise			Remaining			Intrinsic
					Price			Contractual			Value
								Term (in years)
	Outstanding at December 31, 2010		1,394,000		$	3.6			7.61
	Granted		78,000			7.26			9.59
	Exercised		(12,000	)		1.48					$	5.13
	Forfeited		(25,000	)		5.18


	Outstanding at December 31, 2011		1,435,000		$	3.78			6.76
	Granted		652,000			10.19			9.28
	Exercised		(51,000	)		2.4					$	7.56
	Forfeited		(80,000	)		6.31


	Outstanding at December 31, 2012		1,956,000		$	5.86			6.87
	Granted		978,000			25.9			9.26
	Exercised		(496,000	)		2.75					$	26.1
	Forfeited		(103,000	)		16.35


	Outstanding at December 31, 2013		2,335,000		$	14.45			7.49




	Vested or expected to vest at December 31, 2013		2,271,000		$	14.25			7.45
	Exercisable at December 31, 2013		1,020,000		$	6.75			5.7
Schedule of weighted-average assumptions used to estimate the fair value of stock options using the Black-Scholes option pricing model	'






		Year Ended December 31,
		2013			2012			2011
	Weighted-average exercise price of options granted	$	25.9		$	10.19		$	7.26
	Expected volatility		67	%		75	%		77	%
	Expected term (in years)		5.9			6.1			5.8
	Weighted-average risk free interest rate		1.28	%		1.05	%		1.55	%
	Expected dividends		0	%		0	%		0	%
	Weight-average grant date fair value		17.85			7.09			4.83
Schedule of equity-based compensation cost recorded in the statements of operations and comprehensive loss	'






		Year Ended December 31,
		2013			2012			2011
	Research and development	$	3,869,000		$	904,000		$	451,000
	General and administrative		2,634,000			953,000			407,000


		$	6,503,000		$	1,857,000		$	858,000

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
Fair Value Measurements (Tables)	Dec. 31, 2013
Fair Value Measurements	'
Schedule of fair value hierarchy about each major category of financial assets and liabilities measured at fair value on a recurring basis	'






		Fair Value Measurement at December 31, 2013 Using:
		Quoted Prices		Significant		Significant		Balance as of
		in Active		Other		Unobservable		December 31, 2013
		Markets for		Observable		Inputs
		Identical		Inputs		(Level 3)
		Assets		(Level 2)
		(Level 1)
	Assets
	Cash equivalents	$	95,537,000	$	—	$	—	$	95,537,000
	U.S. government agency securities		—		2,003,000		—		2,003,000
	Corporate debt securities		—		53,537,000		—		53,537,000


	Total	$	95,537,000	$	55,540,000	$	—	$	151,077,000









		Fair Value Measurement at December 31, 2012 Using:
		Quoted Prices		Significant		Significant		Balance as of
		in Active		Other		Unobservable		December 31, 2012
		Markets for		Observable		Inputs
		Identical		Inputs		(Level 3)
		Assets		(Level 2)
		(Level 1)
	Assets:
	Cash equivalents	$	71,316,000	$	—	$	—	$	71,316,000


	Total	$	71,316,000	$	—	$	—	$	71,316,000

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2013
Income Taxes	'
Schedule of components of deferred tax assets	'






		December 31,
		2013			2012
	Net operating losses	$	57,010,000		$	38,131,000
	Research & development credits		8,652,000			4,771,000
	Start-up expenditures		5,214,000			5,661,000
	Stock compensation		2,447,000			518,000
	Depreciation		204,000			237,000
	Accruals		160,000			129,000
	Valuation allowance		(73,687,000	)		(49,447,000	)


	Total deferred income taxes	$	—		$	—




Schedule of components of net income tax benefit	'






		2013			2012			2011
	Benefit for income taxes
	Current	$	—		$	—		$	—
	Deferred		24,240,000			14,913,000			4,840,000
	Valuation allowance		(24,240,000	)		(14,913,000	)		(4,840,000	)


	Net income tax benefit	$	—		$	—		$	—




Schedule of reconciliation of difference between benefit for income taxes and income taxes at the statutory U.S. federal income tax rate	'






		2013			2012			2011
	Income tax benefit at statutory rate	$	17,650,000		$	12,512,000		$	3,791,000
	State income taxes, net of federal benefit		2,918,000			1,980,000			595,000
	Research & development credits		1,839,000			542,000			2,926,000
	Return to provision adjustments		2,022,000			475,000			(36,000	)
	Permanent items		(189,000	)		(596,000	)		(324,000	)
	Federal benefit of prior year state deferred items		—			—			(2,112,000	)
	Valuation allowance		(24,240,000	)		(14,913,000	)		(4,840,000	)


	Net benefit	$	—		$	—		$	—




Schedule of reconciliation of the total gross amounts of unrecognized tax benefits	'






		2013			2012			2011
	Balance at beginning of year	$	842,000		$	655,000		$	—
	Additions based on tax positions related to current year		685,000			187,000			655,000
	Reductions for tax positions of prior years		—			—			—
	Settlements		—			—			—


	Balance at end of year	$	1,527,000		$	842,000		$	655,000

Selected_Quarterly_Financial_D1

Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
Selected Quarterly Financial Data (unaudited) (Tables)	Dec. 31, 2013
Selected Quarterly Financial Data (unaudited)	'
Schedule of quarterly financial information	'






		First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	Year Ended December 31, 2013
	License income, net	$	—		$	—		$	—		$	—
	Total operating expenses		13,759,000			11,740,000			11,004,000			13,563,000
	Other income (expense), net		(367,000	)		(518,000	)		(505,000	)		(455,000	)
	Net loss		(14,126,000	)		(12,258,000	)		(11,509,000	)		(14,018,000	)
	Net loss per share, basic and diluted	$	(0.77	)	$	(0.67	)	$	(0.62	)	$	(0.66	)





		First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	Year Ended December 31, 2012
	License income, net	$	1,748,000		$	16,003,000		$	—		$	—
	Total operating expenses		8,680,000			10,868,000			16,362,000			17,779,000
	Other income (expense), net		49,000			(629,000	)		(24,000	)		(257,000	)
	Net (loss) income		(6,883,000	)		4,506,000			(16,386,000	)		(18,036,000	)
	Net (loss) income per share, basic	$	(4.91	)	$	3.17		$	(11.41	)	$	(1.18	)
	Net (loss) income per share, diluted	$	(4.91	)	$	0.32		$	(11.41	)	$	(1.18	)

Organization_and_Basis_of_Pres1

Organization and Basis of Presentation (Details) (USD $)

0 Months Ended

3 Months Ended

12 Months Ended

0 Months Ended

1 Months Ended

0 Months Ended

Sep. 11, 2012

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Nov. 12, 2013

Oct. 15, 2013

Nov. 12, 2013

Oct. 16, 2012

Public Offering

IPO

Organization and Basis of Presentation

Net loss

$14,018,000

$11,509,000

$12,258,000

$14,126,000

$18,036,000

$16,386,000

($4,506,000)

$6,883,000

$51,911,000

$36,799,000

$11,152,000

Accumulated deficit

172,217,000

120,306,000

172,217,000

120,306,000

Net working capital

155,695,000

71,367,000

155,695,000

71,367,000

Cash and cash equivalents, marketable securities and restricted cash

172,120,000

Restricted cash

5,602,000

15,978,000

5,602,000

15,978,000

Remaining borrowing capacity

Reverse stock split ratio

2.6443

Organization and Basis of Presentation

Conversion of redeemable convertible preferred stock into common stock (in shares)

11,545,000

Conversion of warrants for redeemable convertible preferred stock into warrants for common stock (in shares)

365,000

Reclassification of Preferred Stock Warrant Liability to additional paid in capital

3,101,000

Common stock issued (in shares)

2,623,000

5,060,000

Additional shares of common stock purchased by the underwriters through exercise of option

660,000

Offer price of common stock (in dollars per share)

$45.75

$16

Net proceeds from initial public offering after deducting underwriting discounts, commissions and offering related transaction costs

72,479,000

Number of authorized shares of common stock

300,000,000

Number of authorized shares of preferred stock

5,000,000

Additional shares of common stock purchased by the underwriters pursuant to overallotment option

297,000

Proceeds from public offering, net of issuance costs

$124,999,000

$72,479,000

$124,999,000

Summary_of_Significant_Account3

Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	item	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting	'	'	'
Number of operating segments	1	'	'
Cash, Cash Equivalents and Marketable Securities	'	'	'
Impairment charge	$0	'	'
Realized gains or losses from the sale of marketable securities	'	0	0
Restricted Cash	'	'	'
Restricted cash	5,602,000	15,978,000	'
Property and Equipment	'	'	'
Gross	1,360,000	1,318,000	'
Less accumulated depreciation	-1,266,000	-1,043,000	'
Net	94,000	275,000	'
Disposal of property and equipment	0	0	'
Loss on disposal of property and equipment	0	0	4,000
Minimum	'	'	'
Property and Equipment	'	'	'
Estimated useful lives	'1 year	'	'
Maximum	'	'	'
Property and Equipment	'	'	'
Estimated useful lives	'5 years	'	'
Cameras	'	'	'
Property and Equipment	'	'	'
Gross	923,000	923,000	'
Computer hardware and electronics	'	'	'
Property and Equipment	'	'	'
Gross	182,000	147,000	'
Disposal of property and equipment	'	'	54,000
Loss on disposal of property and equipment	'	'	4,000
Furniture and fixtures	'	'	'
Property and Equipment	'	'	'
Gross	234,000	227,000	'
Software	'	'	'
Property and Equipment	'	'	'
Gross	$21,000	$21,000	'

Summary_of_Significant_Account4

Summary of Significant Accounting Policies (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
	item	Dec. 31, 2012	Dec. 31, 2011	License agreement
Revenue Recognition	'	'	'	'
Number of criteria to recognize revenue	4	'	'	'
Maximum number of elements for which no evaluation is required for their treatment as a separate unit of accounting	1	'	'	'
Collaboration Arrangements	'	'	'	'
Non-refundable upfront license fee from Bayer	'	'	'	$21,319,000
Basic and Diluted Net Loss Per Common Share	'	'	'	'
Shares excluded from the calculation of net loss per common share, prior to the use of the treasury stock method, unweighted	2,335,000	1,956,000	13,334,000	'
Comprehensive Income (Loss)	'	'	'	'
Other comprehensive income (loss)	4,000	0	0	'
Reclassifications out of accumulated other comprehensive income related to marketable securities	$0	'	'	'

Marketable_Securities_Details

Marketable Securities (Details) (USD $)	12 Months Ended
Marketable Securities (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013
Marketable securities	'	'	'
Amortized Cost	'	'	$55,536,000
Gross Unrealized Gains	'	'	18,000
Gross Unrealized Losses	'	'	-14,000
Estimated Fair Value	'	'	55,540,000
Realized gains or losses from the sale of marketable securities	0	0	'
Aggregate fair value of available-for-sale investments that have been continuous unrealized loss position for less than 12 months	'	'	20,277,000
Amortized Cost	'	'	'
Mature in one year or less	'	'	33,279,000
Mature after one year through two years	'	'	22,257,000
Amortized cost	'	'	55,536,000
Estimated Fair Value	'	'	'
Mature in one year or less	'	'	33,293,000
Mature after one year through two years	'	'	22,247,000
Estimated Fair Value	'	'	55,540,000
U.S. government agency securities	'	'	'
Marketable securities	'	'	'
Amortized Cost	'	'	2,000,000
Gross Unrealized Gains	'	'	3,000
Estimated Fair Value	'	'	2,003,000
Estimated Fair Value	'	'	'
Estimated Fair Value	'	'	2,003,000
Financial	'	'	'
Marketable securities	'	'	'
Amortized Cost	'	'	33,192,000
Gross Unrealized Gains	'	'	13,000
Gross Unrealized Losses	'	'	-5,000
Estimated Fair Value	'	'	33,200,000
Estimated Fair Value	'	'	'
Estimated Fair Value	'	'	33,200,000
Industrial	'	'	'
Marketable securities	'	'	'
Amortized Cost	'	'	11,081,000
Gross Unrealized Gains	'	'	2,000
Gross Unrealized Losses	'	'	-3,000
Estimated Fair Value	'	'	11,080,000
Estimated Fair Value	'	'	'
Estimated Fair Value	'	'	11,080,000
Other	'	'	'
Marketable securities	'	'	'
Amortized Cost	'	'	9,263,000
Gross Unrealized Losses	'	'	-6,000
Estimated Fair Value	'	'	9,257,000
Estimated Fair Value	'	'	'
Estimated Fair Value	'	'	$9,257,000

Bridge_Financing_Details

Bridge Financing (Details) (USD $)	1 Months Ended	12 Months Ended				81 Months Ended			1 Months Ended		1 Months Ended
	Jan. 31, 2006	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Oct. 31, 2012	31-May-06	Jan. 31, 2006	31-May-06	Jan. 31, 2006	31-May-06
				Series B Redeemable Convertible Preferred Stock Warrants	Series B Redeemable Convertible Preferred Stock Warrants	Series B Redeemable Convertible Preferred Stock Warrants	Series B Redeemable Convertible Preferred Stock Warrants	Series B Redeemable Convertible Preferred Stock Warrants	Convertible notes	Convertible notes	Convertible notes
											Series B Redeemable Convertible Preferred Stock
Bridge Financing	'	'	'	'	'	'	'	'	'	'	'
Aggregate proceeds from issuance of convertible promissory notes and warrants	$8,051,000	'	'	'	'	'	'	'	'	'	'
Interest rate (as a percent)	'	'	'	'	'	'	'	'	'	8.00%	'
Estimated fair value of warrants	'	'	'	'	'	'	'	440,000	'	'	'
Aggregate principal and interest outstanding on the debt instrument converted into shares	'	'	'	'	'	'	'	'	8,247,000	'	'
Number of shares issued on conversion of debt instrument	'	'	'	'	'	'	'	'	'	'	1,084,000
Issue price of shares issued at conversion (in dollars per share)	'	'	'	'	'	'	'	'	'	'	$7.61
Shares issuable upon exercise of warrants (in shares)	'	'	'	'	'	'	243,000	'	'	'	'
Exercise price of warrants (in dollars per share)	'	'	'	'	'	'	$7.61	'	'	'	'
Dividend yield (as a percent)	'	'	'	'	0.00%	'	'	'	'	'	'
Risk-free interest rate (as a percent)	'	'	'	'	0.13%	'	'	'	'	'	'
Volatility rate (as a percent)	'	'	'	'	72.00%	'	'	'	'	'	'
Increase in fair value	'	'	'	'	'	1,205,000	'	'	'	'	'
Interest income (expense)	'	($420,000)	($229,000)	($349,000)	($265,000)	'	'	'	'	'	'
Number of warrants exercised	'	178	'	'	'	'	'	'	'	'	'
Shares of common stock issued as a result of exercise of warrants	'	153,000	'	'	'	'	'	'	'	'	'

Notes_Payable_Details

Notes Payable (Details) (USD $)

12 Months Ended

20 Months Ended

11 Months Ended

12 Months Ended

0 Months Ended

1 Months Ended

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2011

Oct. 31, 2012

Mar. 21, 2011

Oct. 31, 2012

Dec. 31, 2011

Jul. 31, 2012

Feb. 28, 2013

Jan. 31, 2013

Oct. 02, 2012

Jul. 23, 2012

Nov. 30, 2012

Dec. 31, 2013

Aug. 01, 2012

Mar. 21, 2011

Series C redeemable convertible preferred stock warrants

Series D redeemable convertible preferred stock warrants

Senior loan financing

Notes Payable

Maximum borrowing capacity

$15,000,000

Drawn down limit to extend drawdown period

5,000,000

Additional extension to the initial drawdown date (in days)

'60 days

Initial period of interest only payments

'6 months

Fixed rate of interest in initial period (as a percent)

11.50%

Period of payment of interest and principal following the initial period

'30 months

Fixed rate of interest in period following initial period (as a percent)

8.50%

Final payment percentage

6.00%

Amount drawn under credit facility

5,000,000

Amount that the entity can draw, pursuant to the extension obtained

10,000,000

Warrants issued (in shares)

34,000

86,000

Exercise price (in dollars per unit)

$13.35

$13.90

Estimated fair value of warrants

345,000

1,074,000

Amount outstanding under credit facility

15,000,000

5,000,000

Remaining borrowing capacity

Dividend yield (as a percent)

0.00%

Risk-free interest rate (as a percent)

1.75%

1.89%

Volatility rate (as a percent)

80.00%

81.00%

Change in the fair value of warrants

55,000

18,000

Warrant and other income (expense), net

-420,000

-229,000

91,000

36,000

Stock exercised upon issuance of warrants on cashless basis

49,000

Warrants outstanding (in shares)

Amortization of debt issuance costs

340,000

272,000

Interest expense related to the notes payable

1,640,000

169,000

Accrued interest expense

375,000

22,000

Unamortized debt issuance cost

736,000

1,076,000

Future maturities of the Notes payable

2014

5,866,000

2015

5,823,000

2016

552,000

Total

12,241,000

Unamortized debt issuance cost

-736,000

-1,076,000

Notes payable excluding unamortized debt issuance cost

11,505,000

Current portion

-5,526,000

-1,160,000

Notes payable - net of current portion

$5,979,000

$2,764,000

Redeemable_Convertible_Preferr1

Redeemable Convertible Preferred Stock (Details) (USD $)	1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended	1 Months Ended		12 Months Ended
	Oct. 31, 2012	Dec. 31, 2013	Oct. 31, 2012	Dec. 31, 2012	Oct. 31, 2012	Dec. 31, 2012	Oct. 31, 2012	Dec. 31, 2012	Oct. 31, 2012	Aug. 31, 2011	Dec. 31, 2012
	Oct. 31, 2012	Dec. 31, 2013	Series A redeemable convertible preferred stock	Series A redeemable convertible preferred stock	Series B redeemable convertible preferred stock	Series B redeemable convertible preferred stock	Series C redeemable convertible preferred stock	Series C redeemable convertible preferred stock	Series D Redeemable Convertible Preferred Stock	Series D Redeemable Convertible Preferred Stock	Series D Redeemable Convertible Preferred Stock
Redeemable Convertible Preferred Stock	'	'	'	'	'	'	'	'	'	'	'
Preferred stock issued (in shares)	'	'	'	'	'	'	'	'	'	2,692,000	'
Share issue price (in dollars per share)	'	'	'	'	'	'	'	'	'	$13.90	'
Gross proceeds from issuance of stock	'	'	'	'	'	'	'	'	'	$37,425,000	'
Conversion of preferred stock into common stock (in shares)	11,545,000	'	'	-1,806,000	'	-3,981,000	'	-3,023,000	'	'	-2,703,000
Conversion ratio of preferred stock into common stock	'	'	1	'	1.00785	'	1	'	1	'	'
Dividends declared	'	$0	'	'	'	'	'	'	'	'	'

Stockholders_Equity_Details

Stockholders' Equity (Details)	Dec. 31, 2013	Dec. 31, 2012
Common Stock Reserved for Future Issuance	'	'
Common stock awards outstanding (in shares)	2,335,000	1,956,000
Common stock awards available for grant (in shares)	295,000	438,000
Total common shares reserved for future issuance	2,630,000	2,394,000

Stockholders_Equity_Details_2

Stockholders' Equity (Details 2) (USD $)	12 Months Ended
Stockholders' Equity (Details 2) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Number of Shares	'	'	'	'
Outstanding at the end of the period (in shares)	2,335,000	1,956,000	'	'
Aggregate intrinsic value	'	'	'	'
Awards outstanding	$54,180,000	'	'	'
Exercisable	31,280,000	'	'	'
Vested or expected to vest	$52,509,000	'	'	'
Stock options	'	'	'	'
Stock Awards	'	'	'	'
Expiration period	'10 years	'	'	'
Fair market value of common stock (in dollars per share)	$37.35	$30.34	$8.22	'
Number of Shares	'	'	'	'
Outstanding at the beginning of the period (in shares)	1,956,000	1,435,000	1,394,000	'
Granted (in shares)	978,000	652,000	78,000	'
Exercised (in shares)	-496,000	-51,000	-12,000	'
Forfeited (in shares)	-103,000	-80,000	-25,000	'
Outstanding at the end of the period (in shares)	2,335,000	1,956,000	1,435,000	1,394,000
Vested or expected to vest at the end of the period (in shares)	2,271,000	'	'	'
Exercisable at the end of the period (in shares)	1,020,000	'	'	'
Weighted-Average Exercise Price	'	'	'	'
Outstanding at the beginning of the period (in dollars per share)	$5.86	$3.78	$3.60	'
Granted (in dollars per share)	$25.90	$10.19	$7.26	'
Exercised (in dollars per share)	$2.75	$2.40	$1.48	'
Forfeited (in dollars per share)	$16.35	$6.31	$5.18	'
Outstanding at the end of the period (in dollars per share)	$14.45	$5.86	$3.78	$3.60
Vested or expected to vest at the end of the period (in dollars per share)	$14.25	'	'	'
Exercisable at the end of the period (in dollars per share)	$6.75	'	'	'
Weighted-Average Remaining Contractual Term (in years)	'	'	'	'
Outstanding at the beginning of the period	'7 years 5 months 26 days	'6 years 10 months 13 days	'6 years 9 months 4 days	'7 years 7 months 10 days
Granted	'9 years 3 months 4 days	'9 years 3 months 11 days	'9 years 7 months 2 days	'
Outstanding at the end of the period	'7 years 5 months 26 days	'6 years 10 months 13 days	'6 years 9 months 4 days	'7 years 7 months 10 days
Vested or expected to vest at the end of the period	'7 years 5 months 12 days	'	'	'
Exercisable at the end of the period	'5 years 8 months 12 days	'	'	'
Weighted-Average Intrinsic Value	'	'	'	'
Exercised (in dollars per share)	$26.10	$7.56	$5.13	'
Weighted-average assumptions used to estimate the fair value of stock options	'	'	'	'
Weighted-average exercise price of options granted (in dollars per share)	$25.90	$10.19	$7.26	'
Expected volatility (as a percent)	67.00%	75.00%	77.00%	'
Expected term	'5 years 10 months 24 days	'6 years 1 month 6 days	'5 years 9 months 18 days	'
Weighted-average risk free interest rate (as a percent)	1.28%	1.05%	1.55%	'
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%	'
Weight-average grant date fair value (in dollars per share)	$17.85	$7.09	$4.83	'
Stock options \| Employees	'	'	'	'
Stock Awards	'	'	'	'
Vesting period	'4 years	'	'	'
Incentive stock options \| Individuals owning more than 10% \| Minimum	'	'	'	'
Stock Awards	'	'	'	'
Voting power of all classes of stock (as a percent)	10.00%	'	'	'
Incentive stock options \| Individuals owning more than 10% \| Maximum	'	'	'	'
Stock Awards	'	'	'	'
Expiration period	'5 years	'	'	'
Incentive stock options \| 10% Stockholder	'	'	'	'
Stock Awards	'	'	'	'
Voting power of all classes of stock (as a percent)	10.00%	'	'	'
Incentive stock options \| 10% Stockholder \| Minimum	'	'	'	'
Stock Awards	'	'	'	'
Minimum exercise price as a percentage of fair market value (as a percent)	110.00%	'	'	'
Restricted stock units	'	'	'	'
Additional disclosures	'	'	'	'
Units granted (in shares)	62,500	'	'	'
Weighted average grant date fair value of unvested and outstanding units (in dollars per share)	$27.16	'	'	'
2004 Stock Plan	'	'	'	'
Stock Awards	'	'	'	'
Number of shares authorized for grant	3,224,000	2,491,000	2,113,000	'
2012 Equity Incentive Award	'	'	'	'
Stock Awards	'	'	'	'
Threshold number of annual additional shares of common stock available for issuance	1,512,687	'	'	'
Percentage for the threshold number of annual additional shares of common stock available for issuance, expressed as percentage of common stock issued and outstanding on last day of the preceding calendar year	4.00%	'	'	'

Stockholders_Equity_Details_3

Stockholders' Equity (Details 3) (USD $)	12 Months Ended
Stockholders' Equity (Details 3) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock-based compensation expense	'	'	'
Total equity-based compensation cost	$6,503,000	$1,857,000	$858,000
Stock options	'	'	'
Stock-based compensation expense	'	'	'
Unrecognized compensation expense	13,287,000	'	'
Expected weighted-average period of recognition	'2 years 3 months 25 days	'	'
Research and development	'	'	'
Stock-based compensation expense	'	'	'
Total equity-based compensation cost	3,869,000	904,000	451,000
General and administrative	'	'	'
Stock-based compensation expense	'	'	'
Total equity-based compensation cost	$2,634,000	$953,000	$407,000

Stockholders_Equity_Details_4

Stockholders' Equity (Details 4) (USD $)	12 Months Ended
Stockholders' Equity (Details 4) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock Awards	'	'	'
Compensation expense	$6,503,000	$1,857,000	$858,000
Stock options	'	'	'
Stock Awards	'	'	'
Number of shares granted	978,000	652,000	78,000
Dividend yield (as a percent)	0.00%	0.00%	0.00%
Volatility rate (as a percent)	67.00%	75.00%	77.00%
Contractual life	'5 years 10 months 24 days	'6 years 1 month 6 days	'5 years 9 months 18 days
Risk free interest rate (as a percent)	1.28%	1.05%	1.55%
Stock options \| Nonemployees	'	'	'
Stock Awards	'	'	'
Number of shares granted	24,000	16,000	19,000
Exercise price, low end of the range (in dollars per share)	$6.58	'	'
Exercise price, high end of the range (in dollars per share)	$43.69	'	'
Compensation expense	$867,000	$250,000	$50,000
Dividend yield (as a percent)	0.00%	0.00%	0.00%
Volatility rate (as a percent)	60.00%	73.00%	76.00%
Risk free interest rate (as a percent)	1.19%	0.67%	1.38%
Stock options \| Nonemployees \| Maximum	'	'	'
Stock Awards	'	'	'
Contractual life	'10 years	'10 years	'10 years

Commitments_Collaborations_and1

Commitments, Collaborations and Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Commitments, Collaborations and Contingencies	'	'	'
Expected rent expense through July 31, 2014	$246,000	'	'
Rent expense under operating leases associated with new office leases	$409,000	$379,000	$265,000

Commitments_Collaborations_and2

Commitments, Collaborations and Contingencies (Details 2) (USD $)

12 Months Ended

0 Months Ended

1 Months Ended

12 Months Ended

0 Months Ended

1 Months Ended

12 Months Ended

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

31-May-12

Aug. 31, 2010

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

31-May-12

Aug. 31, 2005

Dec. 31, 2013

Dec. 31, 2010

Aug. 31, 2010

Dec. 31, 2013

License agreement

Supply Arrangements

Bayer

LA Biomed

Pfizer

Hospira

item

Minimum

Collaboration Arrangements

Upfront license fee paid

($3,847,000)

($12,984,000)

$21,319,000

Contingent income

297,000,000

Contingent income received

15,800,000

Number of consecutive validated manufacturing lots

Deferred revenue

21,319,000

Restricted cash

15,978,000

5,602,000

17,400,000

22,247,000

Deferred development funds

17,400,000

22,247,000

Period of advance notice which is required to terminate the agreement

'180 days

'90 days

'24 months

Expiration period of royalties from the date of first commercial sale of related product

'15 years

Number of territories into which entry by qualifying competitive product does not result in reduction in royalty payments

Amounts recognized as offsets to research and development expense

11,739,000

10,075,000

14,615,000

Accrued costs related to services performed

2,395,000

1,762,000

Milestone payment

500,000

Non-royalty sublicense fees equal to a certain percentage of sublicense income (as a percent)

10.00%

Maximum non-royalty sublicense fees

5,000,000

Right to issue capital to satisfy payment of sublicense fees (as a percent)

50.00%

Non-royalty sublicense fee expenses

1,580,000

1,950,000

Non-royalty sublicense fee paid

390,000

Remainder of non-royalty sublicense fee

$1,560,000

Non-royalty sublicense fee paid in cash upon initial public offering (as a percent)

50.00%

Non-royalty sublicense fee paid in stock upon initial public offering (as a percent)

50.00%

Period of written notice of uncured material breach, which is required to terminate the agreement

'60 days

Period after receiving invoice during which payments are due to vendor

'30 days

Term of agreement

'5 years

Additional and successive period of extension to initial term of agreement

'2 years

Period of non-performance by other party due to force majeure after which notice can be given to terminate agreement

'180 days

Period following the commercialization during which the vendor has the right to be sole supplier of drug product

'3 years

Right of supply as a percentage of annual requirement of drug product

75.00%

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	12 Months Ended
Fair Value Measurements (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Fair value of financial assets and liabilities measured at fair value on a recurring basis	'	'
Adjustment made to U.S. Treasury securities	$0	$0
Fair value assets, amount transferred between measurement levels	0	0
Fair value liabilities, amount transferred between measurement levels	0	0
Assets:	'	'
Marketable securities	55,540,000	'
U.S. government agency securities and Corporate debt securities	'	'
Fair value of financial assets and liabilities measured at fair value on a recurring basis	'	'
Maximum maturity period	'2 years	'
U.S. government agency securities	'	'
Assets:	'	'
Marketable securities	2,003,000	'
Recurring basis \| U.S. government agency securities	'	'
Assets:	'	'
Marketable securities	2,003,000	'
Recurring basis \| Corporate debt securities	'	'
Assets:	'	'
Marketable securities	53,537,000	'
Recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)	'	'
Assets:	'	'
Cash equivalents	95,537,000	71,316,000
Total	95,537,000	71,316,000
Recurring basis \| Significant Other Observable Inputs (Level 2)	'	'
Assets:	'	'
Total	55,540,000	'
Recurring basis \| Significant Other Observable Inputs (Level 2) \| U.S. government agency securities	'	'
Assets:	'	'
Marketable securities	2,003,000	'
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Corporate debt securities	'	'
Assets:	'	'
Marketable securities	53,537,000	'
Recurring basis \| Total	'	'
Assets:	'	'
Cash equivalents	95,537,000	71,316,000
Total	$151,077,000	$71,316,000

401k_Savings_Plan_Details

401(k) Savings Plan (Details) (USD $)	12 Months Ended
401(k) Savings Plan (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
401(k) Savings Plan	'	'	'
Contribution expense under the 401(k) Plan	$341,000	$208,000	$156,000

Income_Taxes_Details

Income Taxes (Details) (USD $)	12 Months Ended
Income Taxes (Details) (USD $)	Dec. 31, 2013
Income Taxes	'
Provision for income taxes	$0

Income_Taxes_Details_2

Income Taxes (Details 2) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Income Taxes	'	'
Deferred tax assets	$73,687,000	$49,447,000
Deferred tax assets that will be directly credited to additional paid in capital	7,450,000	'
Federal	'	'
Income Taxes	'	'
Net operating loss carryforwards	152,000,000	'
Tax credit carry-forwards	7,200,000	'
State	'	'
Income Taxes	'	'
Tax credit carry-forwards	$4,500,000	'

Income_Taxes_Details_3

Income Taxes (Details 3) (USD $)	12 Months Ended
Income Taxes (Details 3) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net operating losses	'	'	'
NOL carryforwards expiring unutilized	$800,000	'	'
Minimum percentage point aggregate change in ownership, annual limitation	50.00%	'	'
Deferred tax assets	'	'	'
Net operating losses	57,010,000	38,131,000	'
Research & development credits	8,652,000	4,771,000	'
Start-up expenditures	5,214,000	5,661,000	'
Stock compensation	2,447,000	518,000	'
Depreciation	204,000	237,000	'
Accruals	160,000	129,000	'
Valuation allowance	-73,687,000	-49,447,000	'
Components of net income tax benefit	'	'	'
Deferred	24,240,000	14,913,000	4,840,000
Valuation allowance	-24,240,000	-14,913,000	-4,840,000
Net income tax benefit	0	'	'
Reconciliation of difference between for income taxes and income taxes at statutory U.S. federal income tax rate	'	'	'
Income tax benefit at statutory rate	17,650,000	12,512,000	3,791,000
State income taxes, net of federal benefit	2,918,000	1,980,000	595,000
Research & development credits	1,839,000	542,000	2,926,000
Return to provision adjustments	2,022,000	475,000	-36,000
Permanent items	-189,000	-596,000	-324,000
Federal benefit of prior year state deferred items	'	'	-2,112,000
Valuation allowance	-24,240,000	-14,913,000	-4,840,000
Net income tax benefit	0	'	'
Reconciliation of the total gross amounts of unrecognized tax benefits	'	'	'
Balance, at beginning of period	842,000	655,000	'
Additions based on tax positions related to current year	685,000	187,000	655,000
Balance, at end of period	1,527,000	842,000	655,000
Accrued interest and penalties associated with uncertain tax positions	$0	$0	$0

Selected_Quarterly_Financial_D2

Selected Quarterly Financial Data (unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Selected Quarterly Financial Data (unaudited)	'	'	'	'	'	'	'	'	'	'	'
License income, net	'	'	'	'	'	'	$16,003,000	$1,748,000	'	$17,751,000	$11,797,000
Total operating expenses	13,563,000	11,004,000	11,740,000	13,759,000	17,779,000	16,362,000	10,868,000	8,680,000	50,066,000	53,689,000	22,645,000
Other income (expense), net	-455,000	-505,000	-518,000	-367,000	-257,000	-24,000	-629,000	49,000	'	'	'
Net income (loss)	($14,018,000)	($11,509,000)	($12,258,000)	($14,126,000)	($18,036,000)	($16,386,000)	$4,506,000	($6,883,000)	($51,911,000)	($36,799,000)	($11,152,000)
Net income (loss) per share, basic (in dollars per share)	'	'	'	'	($1.18)	($11.41)	$3.17	($4.91)	'	'	'
Net income (loss) per share, diluted (in dollars per share)	'	'	'	'	($1.18)	($11.41)	$0.32	($4.91)	'	'	'
Net income (loss) per share, basic and diluted (in dollars per share)	($0.66)	($0.62)	($0.67)	($0.77)	'	'	'	'	($2.71)	($7.47)	($7.98)

Subsequent_Events_unaudited_De

Subsequent Events (unaudited) (Details) (Subsequent event, USD $)	0 Months Ended	1 Months Ended		1 Months Ended
	Mar. 12, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014
	Facility lease agreement	License agreement	License agreement	License agreement
	sqft	Bayer	Bayer	Bayer
		item	Maximum	Unsecured promissory note
Subsequent events	'	'	'	'
Area of office (in square feet)	24,475	'	'	'
Monthly base rent	$62,000	'	'	'
Annual fixed rate escalation (as a percent)	3.00%	'	'	'
Lease term	'36 months	'	'	'
Additional Lease term	'36 months	'	'	'
Additional area of office (in square feet)	8,723	'	'	'
Total commitment for the initial 36 month term	3,000,000	'	'	'
Total consideration for acquisition of rights to develop and commercialize ATX-101	'	84,000,000	'	'
Value of common stock issued as a part of consideration	'	33,000,000	'	'
Average number of trading days before and after the transaction considered for valuation of common stock issued as a part of consideration.	'	10	'	'
Notes issued as a part of consideration	'	'	'	51,000,000
Interest rate (as a percent)	'	'	'	5.00%
Consideration upon the achievement of certain long-term sales milestone payments on annual sales	'	'	$123,800,000	'