Enanta Pharmaceuticals (ENTA) 10-Q 12 Aug 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Jun. 30, 2014	Aug. 08, 2014
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Entity Registrant Name	'ENANTA PHARMACEUTICALS INC	'
Entity Central Index Key	'0001177648	'
Current Fiscal Year End Date	'--09-30	'
Entity Filer Category	'Non-accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	18,582,628

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Jun. 30, 2014	Sep. 30, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$26,374	$8,859
Short-term marketable securities	69,513	92,621
Accounts receivable	399	808
Unbilled receivables	2,259	784
Deferred tax assets	11,183	'
Prepaid expenses and other current assets	1,950	1,641
Total current assets	111,678	104,713
Property and equipment, net	1,551	1,121
Long-term marketable securities	41,700	10,703
Deferred tax assets	4,149	'
Restricted cash	436	436
Total assets	159,514	116,973
Current liabilities:	'	'
Accounts payable	1,284	1,481
Accrued expenses	2,984	3,035
Deferred revenue	'	10
Total current liabilities	4,268	4,526
Warrant liability	1,675	1,620
Other long-term liabilities	405	359
Total liabilities	6,561	6,505
Commitments and contingencies (Note 11)	'	'
Stockholders' equity:	'	'
Common stock; $0.01 par value; 100,000,000 shares authorized at June 30, 2014 and September 30, 2013; 18,789,536 and 18,138,597 shares issued and 18,580,720 and 17,929,781 shares outstanding at June 30, 2014 and September 30, 2013, respectively	188	181
Additional paid-in capital	220,741	217,741
Treasury stock, at par value; 208,816 shares at June 30, 2014 and September 30, 2013	-2	-2
Accumulated other comprehensive loss	-4	-2
Accumulated deficit	-67,970	-107,450
Total stockholders' equity	152,953	110,468
Total liabilities and stockholders' equity	159,514	116,973
Series 1 Nonconvertible Preferred Stock [Member]	'	'
Current liabilities:	'	'
Series 1 nonconvertible preferred stock	$213	'

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2014	Sep. 30, 2013
Statement Of Financial Position [Abstract]	'	'
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	18,789,536	18,138,597
Common stock, shares outstanding	18,580,720	17,929,781
Treasury stock, shares	208,816	208,816

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement [Abstract]	'	'	'	'
Revenue	$42,051	$1,649	$45,104	$30,704
Operating expenses:	'	'	'	'
Research and development	4,553	4,039	13,538	12,541
General and administrative	2,603	1,788	7,255	4,433
Total operating expenses	7,156	5,827	20,793	16,974
Income (loss) from operations	34,895	-4,178	24,311	13,730
Other income:	'	'	'	'
Interest income	106	64	329	146
Interest expense	-5	-7	-14	-23
Change in fair value of warrant liability and Series 1 nonconvertible preferred stock	-65	-17	-268	217
Total other income, net	36	40	47	340
Income (loss) before income taxes	34,931	-4,138	24,358	14,070
Income tax benefit	15,122	'	15,122	'
Net income (loss)	50,053	-4,138	39,480	14,070
Accretion of redeemable convertible preferred stock to redemption value	'	'	'	-2,526
Net income attributable to participating securities	'	'	'	-13,670
Net income (loss) attributable to common stockholders	$50,053	($4,138)	$39,480	($2,126)
Net income (loss) per share attributable to common stockholders:	'	'	'	'
Basic	$2.70	($0.23)	$2.16	($0.30)
Diluted	$2.61	($0.23)	$2.06	($0.30)
Weighted average common shares outstanding:	'	'	'	'
Basic	18,528,833	17,819,813	18,275,831	7,052,989
Diluted	19,203,270	17,819,813	19,168,368	7,052,989

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (Loss) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement Of Income And Comprehensive Income [Abstract]	'	'	'	'
Net income (loss)	$50,053	($4,138)	$39,480	$14,070
Other comprehensive loss:	'	'	'	'
Net unrealized losses on marketable securities, net of tax of $0	-65	-87	-2	-104
Total other comprehensive loss	-65	-87	-2	-104
Comprehensive income (loss)	$49,988	($4,225)	$39,478	$13,966

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement Of Income And Comprehensive Income [Abstract]	'	'	'	'
Net unrealized losses on marketable securities, tax	$0	$0	$0	$0

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Cash flows from operating activities	'	'
Net income	$39,480	$14,070
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization expense	242	148
Non-cash interest expense	14	23
Change in fair value of warrant liability and Series 1 nonconvertible preferred stock	268	-217
Stock-based compensation expense	1,887	777
Gain on disposal of property and equipment	'	-100
Premium on marketable securities	-1,824	-1,170
Amortization of premium on marketable securities	1,636	697
Benefit from deferred income taxes	-15,228	'
Income tax benefit from the exercise of stock options	-105	'
Change in operating assets and liabilities:	'	'
Accounts receivable	409	173
Unbilled receivables	-1,475	912
Prepaid expenses and other current assets	161	-291
Other assets	'	22
Accounts payable	-190	-620
Accrued expenses	-200	-1,288
Deferred revenue	-10	-17
Other long-term liabilities	46	37
Net cash provided by operating activities	25,111	13,156
Cash flows from investing activities	'	'
Purchases of property and equipment	-543	-404
Purchases of marketable securities	-85,750	-100,253
Sales of marketable securities	7,413	2,454
Maturities of marketable securities	70,164	36,625
Net cash used in investing activities	-8,716	-61,578
Cash flows from financing activities	'	'
Proceeds from exercise of stock options	1,015	437
Income tax benefit from the exercise of stock options	105	'
Proceeds from initial public offering, net of commissions	'	59,892
Payments of initial public offering costs	'	-3,540
Net cash provided by financing activities	1,120	56,789
Net increase in cash and cash equivalents	17,515	8,367
Cash and cash equivalents at beginning of period	8,859	10,511
Cash and cash equivalents at end of period	26,374	18,878
Supplemental disclosure of noncash financing activities:	'	'
Accretion of redeemable convertible preferred stock to redemption value	'	2,526
Conversion of preferred stock into common stock	'	161,808
Exercise of Series 1 warrant into Series 1 nonconvertible preferred stock	$206	'

Nature_of_the_Business_and_Bas

Nature of the Business and Basis of Presentation	9 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
Nature of the Business and Basis of Presentation	'
	1	Nature of the Business and Basis of Presentation
	Enanta Pharmaceuticals, Inc. (the “Company”), incorporated in Delaware in 1995, is a research and development-focused biotechnology company that uses its chemistry-driven approach and drug discovery capabilities to create small molecule drugs primarily in the infectious disease field. The Company is developing novel protease, NS5A, cyclophilin and nucleotide polymerase inhibitors targeted against the hepatitis C virus (“HCV”). Additionally, the Company has created a new class of bridged bicyclic antibiotics known as Bicyclolides to overcome bacterial resistance. Antibacterial focus areas include “superbugs,” respiratory tract infections, and intravenous and oral treatments for hospital and community methicillin-resistant Staphylococcus aureus (“MRSA”).
	The Company is subject to risks common to companies in the biotechnology industry including, but not limited to, difficulties in developing new therapies, competition from innovations of others, dependence on collaborative arrangements, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the need for financial resources to fund research and development activities. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure, and extensive compliance reporting capabilities.
	Unaudited Interim Financial Information
	The consolidated balance sheet at September 30, 2013 was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America (“GAAP”). The accompanying unaudited consolidated financial statements as of June 30, 2014 and for the three and nine months ended June 30, 2014 and 2013 have been prepared by the Company, pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. These financial statements should be read in conjunction with the Company’s audited financial statements and the notes thereto for the year ended September 30, 2013 included in the Company’s 2013 Annual Report on Form 10-K.
	In the opinion of management, all adjustments, consisting only of normal recurring adjustments necessary for a fair statement of the Company’s financial position as of June 30, 2014 and results of operations for the three and nine months ended June 30, 2014 and 2013 and cash flows for the nine months ended June 30, 2014 and 2013 have been made. The results of operations for the nine months ended June 30, 2014 are not necessarily indicative of the results of operations that may be expected for the year ending September 30, 2014.
	The accompanying consolidated financial statements have been prepared in conformity with GAAP. All dollar amounts in the consolidated financial statements and in the notes to the consolidated financial statements, except share and per share amounts, are in thousands unless otherwise indicated.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	9 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	2	Summary of Significant Accounting Policies
	Use of Estimates
	The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, management’s judgments of separate units of accounting and best estimate of selling price of those units of accounting within its revenue arrangements; the valuation of common stock for the periods prior to the completion of the Company’s initial public offering (“IPO”), valuation of warrants, Series 1 nonconvertible preferred stock and stock-based awards; the useful lives of property and equipment; and the accounting for income taxes, including uncertain tax positions and the valuation of net deferred tax assets. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates.
	Revenue Recognition
	The Company’s revenue is generated primarily through collaborative research and license agreements. The terms of these agreements contain multiple deliverables, which may include (i) licenses, (ii) research and development activities, and (iii) participation in joint research and development steering committees. The terms of these agreements may include nonrefundable upfront license fees, payments for research and development activities, payments based upon the achievement of certain milestones, and royalty payments based on product sales derived from the collaboration. In all instances, revenue is recognized only when the price is fixed or determinable, persuasive evidence of an arrangement exists, delivery has occurred or the services have been rendered, collectibility of the resulting receivable is reasonably assured, and the Company has fulfilled its performance obligations under the contract.
	For multiple element agreements entered into or materially modified after October 1, 2011, the Company applies the principles included in Accounting Standards Update (“ASU”) No. 2009-13, Multiple-Deliverable Revenue Arrangements (“ASU 2009-13”) to account for revenue. Under this guidance the selling prices of deliverables under the arrangement may be derived using third-party evidence (“TPE”) or a best estimate of selling price (“BESP”), if vendor specific objective evidence (“VSOE”) is not available. The objective of BESP is to determine the price at which the Company would transact a sale if the element within the license agreement was sold on a standalone basis. Establishing BESP involves management’s judgment and considers multiple factors, including market conditions and company-specific factors including those factors contemplated in negotiating the agreements as well as internally developed models that include assumptions related to market opportunity, discounted cash flows, estimated development costs, probability of success, and the time needed to commercialize a product candidate pursuant to the license. In validating the Company’s BESP, the Company considers whether changes in key assumptions used to determine the BESP will have a significant effect on the allocation of the arrangement consideration between the multiple deliverables. Deliverables under the arrangement are separate units of accounting if (i) the delivered item has value to the customer on a standalone basis, and (ii) if the arrangement includes a general right of return relative to the delivered item, delivery or performance of the undelivered item is considered probable and substantially within the control of the Company. The arrangement consideration that is fixed or determinable at the inception of the arrangement is allocated to the separate units of accounting based on their relative selling prices. The appropriate revenue recognition model is applied to each element, and revenue is accordingly recognized as each element is delivered. The Company may exercise significant judgment in determining whether a deliverable is a separate unit of accounting.
	In determining the separate units of accounting, the Company evaluates whether the license has standalone value to the collaborator based on consideration of the relevant facts and circumstances for each arrangement. Factors considered in this determination include the research and development capabilities of the collaborator and the availability of relevant research expertise in the marketplace. In addition, the Company considers whether or not (i) the collaborator can use the license for its intended purpose without the receipt of the remaining deliverables, (ii) the value of the license is dependent on the undelivered items, and (iii) the collaborator or other vendors can provide the undelivered items.
	Under a collaborative research and license agreement, a steering committee is typically responsible for overseeing the general working relationships, determining the protocols to be followed in the research and development performed, and evaluating the results from the continued development of the product in order to determine the clinical studies to be performed. The Company evaluates whether its participation in joint research and development steering committees is a substantive obligation or whether the services are considered inconsequential or perfunctory. The Company’s participation on a steering committee is considered “participatory” and therefore accounted for as a separate element when the collaborator requires the participation of the Company to ensure all elements of an arrangement are maximized. Steering committee services that are considered participatory are combined with other research services or performance obligations required under an arrangement, if any, in determining the level of effort required in an arrangement and the period over which the Company expects to complete its aggregate performance obligations. Alternatively, the Company’s participation on a steering committee is considered “protective” and therefore not accounted for as a separate element in a case where the Company can exercise or control when to be involved at its own discretion. Factors the Company considers in determining if its participation in a joint steering committee is participating or protective include: (i) which party negotiated or requested the steering committee, (ii) how frequently the steering committee meets, (iii) whether or not there are any penalties or other recourse if the Company does not attend the steering committee meetings, (iv) which party has decision making authority on the steering committee, and (v) whether or not the collaborator has the requisite experience and expertise associated with the research and development of the licensed intellectual property.
	For agreements entered into prior to October 1, 2011, the Company accounted for the multiple elements within the agreements as a single unit of accounting and all payments received were recognized as revenue over the estimated period of performance of the entire arrangement as the Company was not able to separately recognize revenue for the elements under the provisions of previously applicable revenue recognition guidance.
	For all periods presented, whenever the Company determines that an element is delivered over a period of time, revenue is recognized using either a proportional performance model or a straight-line model over the period of performance, which is typically the research and development term. Full-time equivalents (“FTEs”) are typically used as the measure of performance. At each reporting period, the Company reassesses its cumulative measure of performance and makes appropriate adjustments, if necessary. The Company recognizes revenue using the proportional performance model whenever the Company can make reasonably reliable estimates of the level of effort required to complete its performance obligations under an arrangement. Revenue recognized under the proportional performance model at each reporting period is determined by multiplying the total expected payments under the contract (excluding royalties and payments contingent upon achievement of milestones) by the ratio of the level of effort incurred to date to the estimated total level of effort required to complete the performance obligations under the arrangement. Revenue is limited to the lesser of the cumulative amount of payments received or the cumulative amount of revenue earned, as determined using the proportional performance model as of each reporting period. Alternatively, if the Company cannot make reasonably reliable estimates the level of effort required to complete its performance obligations under an arrangement, then revenue under the arrangement is recognized on a straight-line basis over the period expected to complete the Company’s performance obligations. If and when a contingent milestone payment is earned, the additional consideration to be received is allocated to the separate units of accounting in the arrangement based on their relative selling prices at the inception of the arrangement. Revenue is limited to the lesser of the cumulative amount of payments received or the cumulative amount of revenue earned, as determined on a straight-line basis as of the period end date. If the Company cannot reasonably estimate when its performance obligation period ends, then revenue is deferred until the Company can reasonably estimate when the performance obligation period ends.
	Royalty revenue, if any, is recognized based on contractual terms when reported sales are reliably measurable and collectibility is reasonably assured, provided that there are no performance obligations then remaining. To date, none of the Company’s products have been approved, and therefore the Company has not earned any royalty revenue from product sales.
	During the three and nine months ended June 30, 2014 and 2013 the Company also generated revenue from a government contract, under which the Company is reimbursed for certain allowable costs for the funded project. Revenue from the government contract is recognized when the related service is performed. The related costs incurred by the Company under the government contract are included in research and development expenses in the statements of operations.
	Amounts received prior to satisfying all revenue recognition criteria are recorded as deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized as revenue within the next twelve months of the consolidated balance sheet date are classified as long-term deferred revenue.
	In the event that a collaborative research and license agreement is terminated and the Company then has no further performance obligations, the Company recognizes as revenue any amounts that had not previously been recorded as revenue but were classified as deferred revenue at the date of such termination.
	Recently Issued Accounting Pronouncements
	In May, 2014, the Financial Accounting Standards Board issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the Company expects to receive for those goods or services. The new standard will be effective for the Company on October 1, 2017. The Company is currently evaluating the potential impact that Topic 606 may have on its financial position and results of operations.

Fair_Value_of_Financial_Assets

Fair Value of Financial Assets and Liabilities	9 Months Ended
	Jun. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value of Financial Assets and Liabilities	'
	3	Fair Value of Financial Assets and Liabilities
	The following tables present information about the Company’s financial assets and liabilities that were subject to fair value measurement on a recurring basis as of June 30, 2014 and September 30, 2013 and indicate the fair value hierarchy of the valuation inputs utilized to determine such fair value:
		Fair Value Measurements as of June 30, 2014 Using:
		Level   1			Level   2		Level   3		Total
	Assets:
	Cash equivalents	$	21,972		$	—	$	—	$	21,972
	Commercial paper		—			11,840		—		11,840
	Corporate bonds		—			93,860		—		93,860
	U.S. Agency bonds		—			5,513		—		5,513
		$	21,972		$	111,213	$	—	$	133,185
	Liabilities:
	Warrant liability	$	—		$	—	$	1,675	$	1,675
	Series 1 nonconvertible preferred stock		—			—		213		213
		$	—		$	—	$	1,888	$	1,888
		Fair Value Measurements as of September 30, 2013  Using:
		Level 1			Level 2		Level 3		Total
	Assets:
	Cash equivalents	$	7,517		$	—	$	—	$	7,517
	U.S. Treasury notes		1,005			—		—		1,005
	Commercial paper		—			10,596		—		10,596
	Corporate bonds		—			84,755		—		84,755
	U.S. Agency bonds		—			3,518		—		3,518
	Certificate of deposit		—			3,450		—		3,450
		$	8,522		$	102,319	$	—	$	110,841
	Liabilities:
	Warrant liability	$	—		$	—	$	1,620	$	1,620
		$	—		$	—	$	1,620	$	1,620
	Cash equivalents at June 30, 2014 and September 30, 2013 consist of money market funds.
	During the three and nine months ended June 30, 2014 and 2013, there were no transfers between Level 1, Level 2 and Level 3.
	As of June 30, 2014 and September 30, 2013, respectively, the warrant liability was comprised of the values of warrants for the purchase of Series 1 nonconvertible preferred stock measured at fair value. At June 30, 2014 the outstanding Series 1 nonconvertible preferred stock was also measured at fair value based on significant inputs not observable in the market, which represented a Level 3 measurement within the fair value hierarchy. The Company utilized a probability-weighted valuation model which took into consideration various outcomes that may require the Company to transfer assets and which determined that the fair value of the Series 1 warrants was $1,675 and $1,620, at June 30, 2014 and September 30, 2013, respectively. The fair value of Series 1 nonconvertible preferred stock was $213 as of June 30, 2014. Changes in the fair value of the warrant liability and Series 1 nonconvertible preferred stock are recognized in the consolidated statements of operations.
	The recurring Level 3 fair value measurements of the Company’s warrant liability and Series 1 nonconvertible preferred stock using probability-weighted discounted cash flow include the following significant unobservable inputs:
		Unobservable Input		Range
				(Weighted
				Average)
	Warrant liability and Series 1 nonconvertible preferred stock	Probabilities of payout		70%–90%
		Periods in which payout is expected to occur		2015–2016
		Discount rate		4.25%
	The following table provides a rollforward of the aggregate fair values of the Company’s warrants for the purchase of Series 1 nonconvertible preferred stock and the outstanding Series 1 nonconvertible preferred stock for which fair value is determined by Level 3 inputs:
		Warrants			Series 1
					nonconvertible
					preferred
					stock
	Balance, September 30, 2013	$	1,620		$	—
	Warrants exercised		(206	)		206
	Increase in fair value		261			7
	Balance, June 30, 2014	$	1,675		$	213

Marketable_Securities

Marketable Securities	9 Months Ended
	Jun. 30, 2014
Investments Debt And Equity Securities [Abstract]	'
Marketable Securities	'
	4	Marketable Securities
	As of June 30, 2014 and September 30, 2013, the fair value of available-for-sale marketable securities by type of security was as follows:
			June 30, 2014
			Amortized Cost		Gross Unrealized		Gross Unrealized			Fair Value
					Gains		Losses
	Commercial paper		$	11,840	$	—	$	—		$	11,840
	Corporate bonds			93,861		44		(45	)		93,860
	U.S. Agency bonds			5,516		—		(3	)		5,513
			$	111,217	$	44	$	(48	)	$	111,213
			September 30, 2013
			Amortized Cost		Gross Unrealized		Gross Unrealized			Fair Value
					Gains		Losses
	Commercial paper		$	10,596	$	—	$	—		$	10,596
	Corporate bonds			84,757		23		(25	)		84,755
	U.S. Agency bonds			3,519		—		(1	)		3,518
	Certificate of deposit			3,450		—		—			3,450
	U.S. Treasury notes			1,004		1		—			1,005
			$	103,326	$	24	$	(26	)	$	103,324
	As of June 30, 2014, marketable securities consisted of investments that mature within one year, with the exception of certain corporate bonds, which have maturities within three years and an aggregate fair value of $41,700.

Accrued_Expenses_and_Other_Lon

Accrued Expenses and Other Long-Term Liabilities	9 Months Ended
	Jun. 30, 2014
Payables And Accruals [Abstract]	'
Accrued Expenses and Other Long-Term Liabilities	'
	5	Accrued Expenses and Other Long-Term Liabilities
	Accrued expenses (current) and other long-term liabilities consisted of the following as of June 30, 2014 and September 30, 2013:
			June 30,		September 30,
			2014		2013
	Accrued expenses:
	Accrued payroll and related expenses		$	953	$	1,041
	Accrued preclinical and clinical expenses			623		127
	Accrued vendor manufacturing			477		989
	Accrued professional fees			336		378
	Present value of accrued third-party license fees			247		240
	Accrued other			348		260
			$	2,984	$	3,035
	Other long-term liabilities:
	Present value of accrued third-party license fees		$	190	$	127
	Accrued rent expense			147		184
	Asset retirement obligation			68		48
			$	405	$	359

Collaboration_Agreements

Collaboration Agreements	9 Months Ended
	Jun. 30, 2014
Organization Consolidation And Presentation Of Financial Statements [Abstract]	'
Collaboration Agreements	'
	6	Collaboration Agreements
	AbbVie Collaboration
	On November 27, 2006, the Company entered into a Collaborative Development and License Agreement (the “AbbVie Agreement”) with Abbott Laboratories to identify, develop and commercialize HCV NS3 and NS3/4A protease inhibitor compounds, including ABT-450. The agreement, which was amended in January and December 2009, was assigned by Abbott to AbbVie Inc. on January 1, 2013 in connection with Abbott’s transfer of its research-based pharmaceuticals business to AbbVie. Under the terms of the AbbVie Agreement, as amended, AbbVie paid to the Company upfront license payments and FTE reimbursements to fund research activities. The Company is also eligible to receive milestone payments for the successful development by AbbVie of one or more HCV compounds as well as tiered royalties per product ranging from the low double digits up to twenty percent, or on a blended basis from the low double digits up to the high teens, on net sales by AbbVie allocable to the collaboration’s protease inhibitors. Deliverables under the AbbVie Agreement included a license, research services and participation on a steering committee. The Company concluded that all deliverables under the AbbVie Agreement should be treated as a single unit of accounting. Accordingly, revenue was recognized using the proportional performance model over the period during which the Company performed research services. The Company completed all remaining obligations under the agreement as of June 2011. All milestone payments received after June 2011 are recognized as revenue when each milestone is achieved by AbbVie.
	Through June 2011, under the AbbVie Agreement the Company had received upfront license payments, research funding, and milestone payments totaling $92,450, all of which were recognized as revenue as of June 30, 2011.
	In December 2012, the Company received an additional $15,000 milestone payment under the AbbVie Agreement as a result of AbbVie’s initiation of dosing in a Phase 3 clinical trial involving ABT-450. This amount was recognized as revenue during the nine months ended June 30, 2013.
	In the quarter ending June 30, 2014, the Company received and recognized as revenue a total of $40,000 in milestone payments from AbbVie as a result of its U.S. regulatory filing with the FDA and a comparable European Union regulatory filing with the EMA for the first regimen containing a collaboration compound.
	The Company is eligible to receive additional milestone payments totaling up to $155,000 upon AbbVie’s achievement of commercial regulatory approval milestones in selected world markets. The Company is also eligible to receive additional milestone payments totaling up to $80,000 upon AbbVie’s achievement of similar commercial regulatory approval milestones for each additional product containing a new protease inhibitor.
	Novartis Collaboration
	On February 16, 2012, the Company entered into a license and collaboration agreement with Novartis (the “Novartis Agreement”) for the development, manufacture and commercialization of its lead development candidate, EDP-239, from its NS5A HCV inhibitor program. Under the terms of the Novartis Agreement, Novartis agreed to pay a nonrefundable upfront fee to the Company and reimbursement of manufacturing and quality assurance expenses related to EDP-239 totaling $34,442. Under the agreement, the Company is eligible to receive aggregate milestone payments of up to $406,000 upon Novartis’ initiation of clinical trials, achievement of regulatory approvals, and/or net sales of products containing the Company’s NS5A inhibitors. The Company is also eligible to receive tiered royalties ranging on a blended basis from the low double digits up to the high teens on net product sales by Novartis allocable to the collaboration’s NS5A inhibitors. Under the agreement, a clinical milestone payment of $11,000 was due to the Company upon Novartis’ initiation of dosing in the first Phase 1 clinical trial involving EDP-239 or another NS5A inhibitor, and was received by the Company in January 2013. An additional milestone payment of $15,000 will be due upon Novartis’ initiation of the first Phase 2 clinical trial using a combination containing an NS5A inhibitor. In addition, Novartis agreed to fund research activities for one year commencing February 2012, up to a total of $1,800. In March 2013, the agreement was amended to extend research funding for an additional six months through August 2013 at the same reimbursement rate.
	The Company determined that the deliverables under the Novartis Agreement were the license and the research services. As each of these deliverables had standalone value it was determined that they each represented a separate unit of accounting. Arrangement consideration was allocated between the license and research services based on their relative selling prices using best estimate of selling price.
	During the three and nine months ended June 30, 2014 the company recognized no revenue under the Novartis Agreement. During the three and nine months ended June 30, 2013 the Company recognized total revenue of $473 and $12,350, respectively, related to the delivery of the license and the performance of the research services under the Novartis Agreement.
	NIAID Contract
	On September 30, 2011, the Company entered into a contract with the National Institute of Allergy and Infectious Diseases (“NIAID”), a division of the National Institutes of Health (“NIH”), which could provide up to $42,700 in development funding to the Company over a five-year period. The contract will fund the preclinical and clinical development of a new class of bridged bicyclic antibiotics known as Bicyclolides to be used as medical countermeasures against multiple biodefense Category A and B bacteria.
	The contract had an initial term of 30 months which ended on March 30, 2014. NIAID has the option to extend the contract up to six times. If each extension option is exercised, the contract would be extended until September 30, 2016. The initial award under the initial term was $14,300, with the possibility of up to a total of $42,700 if each option period is exercised by NIAID. In August 2013 NIAID exercised the first two options under this agreement which obligate it to provide an additional $9,200 in funding to the Company for preclinical and early clinical development of EDP-788, bringing total funding paid or committed to date by NIAID to approximately $23,500 through February 2015.
	The Company recognizes revenue under this agreement as development services are performed in accordance with the funding agreement. During the three months ended June 30, 2014 and 2013, $2,051 and $1,176 of revenue, respectively, was recognized under this agreement. During the nine months ended June 30, 2014 and 2013, the Company recognized revenue of $5,104 and $3,354, respectively.
	The Company recognizes revenue under this agreement as development services are performed in accordance with the funding agreement. During the three months ended June 30, 2014 and 2013, $2,051 and $1,176 of revenue, respectively, was recognized under this agreement. During the nine months ended June 30, 2014 and 2013, the Company recognized revenue of $5,104 and $3,354, respectively.

Warrants_to_Purchase_Series_1_

Warrants to Purchase Series 1 Nonconvertible Preferred Stock and Series 1 Nonconvertible Preferred Stock	9 Months Ended
	Jun. 30, 2014
Equity [Abstract]	'
Warrants to Purchase Series 1 Nonconvertible Preferred Stock and Series 1 Nonconvertible Preferred Stock	'
	7	Warrants to Purchase Series 1 Nonconvertible Preferred Stock and Series 1 Nonconvertible Preferred Stock
	In October and November 2010, the Company issued warrants to purchase up to a total of 1,999,989 shares of Series 1 nonconvertible preferred stock, which expire on October 4, 2017. As these warrants are free-standing financial instruments that may require the Company to transfer assets upon exercise, these warrants are classified as liabilities. The Company is required to remeasure the fair value of these preferred stock warrants at each reporting date, with any adjustments recorded within the change in fair value of warrant liability included in other income (expense) in the consolidated statement of operations. On February 5, 2014, 225,408 warrants were exercised resulting in the net issuance of 223,153 shares of Series 1 nonconvertible preferred stock. As of June 30, 2014, the total fair value of the Series 1 nonconvertible preferred stock was $213. The warrants and Series 1 nonconvertible preferred stock were remeasured at each reporting period, resulting in expense of $65 and $17 for the three months ended June 30, 2014 and 2013, respectively, and expense of $268 and income of $217 for the nine months ended June 30, 2014 and 2013, respectively. As of June 30, 2014 and September 30, 2013, the total fair value of the Series 1 nonconvertible preferred stock warrants was $1,675 and $1,620, respectively.

StockBased_Awards

Stock-Based Awards	9 Months Ended
	Jun. 30, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock-Based Awards	'
	8	Stock-Based Awards
	2012 Equity Incentive Plan
	The Company’s 2012 Equity Incentive Plan (the “2012 Plan”) permits the Company to sell or issue common stock or restricted common stock, to grant incentive stock options or nonqualified stock options for the purchase of common stock, or to grant restricted stock units, stock appreciation rights or other cash incentive awards, to employees, members of the board of directors and consultants of the Company. Upon initial approval, the total number of shares of common stock that could be issued under the plan was 348,355. The number of shares of common stock that may be issued under the 2012 Plan is subject to increase by the number of shares forfeited under any options terminated and not exercised under the previous plan, known as the 1995 Equity Incentive Plan as well as by a number of additional shares on the first day of each fiscal year equal to the lowest amount among the following: (i) 3% of the Company’s outstanding shares of common stock as of that date, (ii) 2,088,167 shares of common stock, or (iii) a lower amount determined by the board of directors. As of June 30, 2014, 410,380 shares remained available for future grant.
	In March 2013, the Company granted to certain executives 167,052 options that vest upon the achievement of certain performance-based targets. The fair value of these options is $2,479. During the nine months ended June 30, 2014, one performance-based target was achieved and the Company recorded compensation expense of $206 related to that target.
	Employee Stock Purchase Plan
	Under the Employee Stock Purchase Plan (the “ESPP”), a total of 185,614 shares of common stock were reserved for issuance. As of June 30, 2014, the Company has not commenced any offering under the ESPP and no shares have been issued.
	Stock Option Valuation
	The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. Prior to March 2013 the Company historically had been a private company and lacked sufficient company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a selected group of publicly traded peer companies, inclusive of the Company, commencing March 2013, and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded stock price. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. The relevant data used to determine the value of the stock option grants is as follows, presented on a weighted average basis:
		Three Months Ended June 30,						Nine Months Ended June 30,
		2014			2013			2014			2013
	Risk-free interest rate		1.93	%		1.16	%		1.89	%		1.03	%
	Expected term (in years)		6.1			6			6.06			6.09
	Expected volatility		76	%		77	%		75	%		73	%
	Expected dividend yield		0	%		0	%		0	%		0	%
	The Company recognizes compensation expense for only the portion of awards that are expected to vest. In developing a forfeiture rate estimate, the Company has considered its historical experience to estimate pre-vesting forfeitures for service-based awards. The impact of a forfeiture rate adjustment will be recognized in full in the period of adjustment, and if the actual forfeiture rate is materially different from the Company’s estimate, the Company may be required to record adjustments to stock-based compensation expense in future periods.
	As required by the 2012 Plan, the exercise price for awards granted is not to be less than the fair value of common shares as of the date of grant. For periods prior to the IPO, the Company valued its common stock by taking into consideration its most recently available valuation of common shares performed by management and the board of directors as well as additional factors which may have changed since the date of the most recent contemporaneous valuation through the date of grant. For periods after the IPO, the Company based fair value of its common stock on the quoted market price.
	The following table summarizes stock option activity during the nine months ended June 30, 2014:
		Shares			Weighted			Weighted			Aggregate
		Issuable			Average			Average			Intrinsic
		Under			Exercise			Remaining			Value
		Options			Price			Contractual
								Term
					(in years)
	Outstanding as of September 30, 2013		1,583,031		$	5.15			5		$	28,133
	Granted		483,570			29.73
	Exercised		(650,939	)		1.56
	Forfeited		(9,343	)		14
	Expired		(465	)		0.73
	Outstanding as of June 30, 2014		1,405,854		$	15.21			7.4		$	38,818
	Options vested and expected to vest as of June 30, 2014		1,221,172		$	15.2			7.2		$	34,028
	Options exercisable as of June 30, 2014		676,867		$	6.42			5.6		$	24,960
	The Company recorded stock-based compensation expense for the three and nine months ended June 30, 2014 and 2013 in the following expense categories:
		Three Months Ended						Nine Months Ended
		June 30,						June 30,
		2014			2013			2014			2013
	Research and development	$	196		$	107		$	562		$	286
	General and administrative		580			132			1,325			491
		$	776		$	239		$	1,887		$	777
	As of June 30, 2014, the Company had an aggregate of $9,067 of unrecognized stock-based compensation cost, which is expected to be recognized over a weighted average period of 3.0 years.

Net_Income_Loss_Per_Share

Net Income (Loss) Per Share	9 Months Ended
	Jun. 30, 2014
Earnings Per Share [Abstract]	'
Net Income (Loss) Per Share	'
	9	Net Income (Loss) Per Share
	Basic and diluted net income (loss) per share attributable to common stockholders was calculated as follows for the three and nine months ended June 30, 2014 and 2013, respectively:
		Three Months Ended					Nine Months Ended
		June 30,					June 30,
		2014		2013			2014		2013
	Basic net income (loss) per share attributable to common stockholders:
	Numerator:
	Net income (loss)	$	50,053	$	(4,138	)	$	39,480	$	14,070
	Accretion of redeemable convertible preferred stock to redemption value		—		—			—		(2,526	)
	Net income attributable to participating securities		—		—			—		(13,670	)
	Net income (loss) attributable to common stockholders	$	50,053	$	(4,138	)	$	39,480	$	(2,126	)
	Denominator:
	Weighted average common shares outstanding—basic		18,528,833		17,819,813			18,275,831		7,052,989
	Net income (loss) per share attributable to common stockholders—basic	$	2.7	$	(0.23	)	$	2.16	$	(0.30	)
	Diluted net income (loss) per share attributable to common stockholders:
	Numerator:
	Net income (loss)	$	50,053	$	(4,138	)	$	39,480	$	14,070
	Accretion of redeemable convertible preferred stock to redemption value		—		—			—		(2,526	)
	Net income attributable to participating securities		—		—			—		(13,670	)
	Net income (loss) attributable to common stockholders—diluted	$	50,053	$	(4,138	)	$	39,480	$	(2,126	)
	Denominator:
	Weighted average common shares outstanding—basic		18,528,833		17,819,813			18,275,831		7,052,989
	Dilutive effect of common stock equivalents		674,437		—			892,537		—
	Weighted average common shares outstanding—diluted		19,203,270		17,819,813			19,168,368		7,052,989
	Net income (loss) per share attributable to common stockholders—diluted	$	2.61	$	(0.23	)	$	2.06	$	(0.30	)
	Stock options for the purchase of 433,535 and 1,525,952 weighted average shares were excluded from the computation of diluted net income per share attributable to common stockholders for the three months ended June 30, 2014 and 2013, respectively, because those options had an anti-dilutive impact due to either the net loss attributable to common stockholders incurred for the period or to the assumed proceeds per share using the treasury stock method being greater than the average fair value of the Company’s common shares for those periods. Stock options for the purchase of 300,428 and 1,685,921 weighted average shares were excluded from the computation of diluted net income per share attributable to common stockholders for the nine months ended June 30, 2014 and 2013, respectively, because those options had an anti-dilutive impact due to either the net loss attributable to common stockholders incurred for the period or to the assumed proceeds per share using the treasury stock method being greater than the average fair value of the Company’s common shares for those periods.

Income_Taxes

Income Taxes	9 Months Ended
	Jun. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	10	Income Taxes
	As of September 30, 2013, December 31, 2013 and March 31, 2014, the Company had provided a valuation allowance for the full amount of its net deferred tax assets because it was not more likely than not that any future benefit from deductible temporary differences and net operating loss and tax credit carry forwards would be realized. At June 30, 2014, the Company reassessed the need for a valuation allowance against its deferred tax assets as the Company earned and collected $40,000 in milestone payments during the three months ended June 30, 2014 as a result of U.S. and European Union regulatory approval filing by AbbVie with respect to the collaboration’s leading product candidate. The Company concluded that it was more likely than not that it would be able to realize its deferred tax assets primarily as a result of historical profitability for the years 2010 through 2013, expected profitability for the year ending September 30, 2014 and forecasted future profits resulting from future expected milestone payments and on-going royalty payments from collaboration partners. Accordingly, the Company reversed its valuation allowance and recorded an income tax benefit of approximately $15,122 for each of the three and nine months ended June 30, 2014. The reversal of the valuation allowance released approximately $22,892, of which $15,333 was recorded as a discrete item in the period ended June 30, 2014 representing the change in estimate regarding future years’ income, and the remaining $7,559 was released to income as the deferred tax assets were utilized in fiscal 2014.
	The effective tax rate benefit for the first nine months of fiscal 2014 was (80.70)% and differs from the federal statutory rate of 34% primarily due to a change in estimate as to the Company’s ability to utilize net operating loss carry-forwards and research and development credits resulting in a reduction of the Company’s valuation allowance against deferred tax assets in the amount of $22,892, as well as changes in estimates related to the fiscal 2014 research and development credits, and certain expenditures which are permanently not deductible for tax purposes.
	The effective tax rate benefit for the first nine months of fiscal 2013 was 0% and differed from the federal statutory tax rate of 34% primarily because the Company had available tax loss carryforwards and other deferred tax assets to offset its taxable income in that period. The Company had concluded in that period, based on the weight of available evidence, that its net deferred tax assets were not more likely than not to be realized in the future. Accordingly, a full valuation allowance had been established against the deferred tax assets as of June 30, 2013.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Jun. 30, 2014
Commitments And Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	11	Commitments and Contingencies
	Leases
	The Company has an office and laboratory lease that expires in September 2018. Payment escalation as specified in the lease agreement is accrued such that rent expense is recognized on a straight-line basis over the term of occupancy. The Company recorded rent expense of $237 for the three months ended June 30, 2014 and 2013, and $711 for the nine months ended June 30, 2014 and 2013.
	In connection with the lease, the Company has outstanding a $436 letter of credit, collateralized by a money market account. As of June 30, 2014 and September 30, 2013, the Company classified $436 related to the letter of credit as restricted cash.
	Intellectual Property Licenses
	The Company has a non-exclusive intellectual property license agreement under which it is required to pay the licensor future license fees of $250 and $200 in fiscal years 2014 and 2015, respectively. In addition, the Company is required to pay (1) annual maintenance fees of $105 for each year that the agreement remains in effect in order to maintain the right to use the license, and (2) a one-time fee of $50 in each circumstance in which the Company provides the licensed intellectual property to one of its collaborators with the prior consent of the licensor. As of June 30, 2014, the Company had accrued expense relating to this obligation of $437, of which $247 was included in accrued expenses and $190 was included in other long-term liabilities.
	The Company also has a non-exclusive license with respect to patents it uses in its HCV research. Under the license, the Company is obligated to pay milestones totaling up to $5,000, plus low single digit royalties, for each HCV product it develops outside of its collaboration with AbbVie or any other collaboration it may enter into in the future with a partner that has licensed these patents.
	Litigation and Contingencies Related to Use of Intellectual Property
	From time to time, the Company may become subject to legal proceedings, claims and litigation arising in the ordinary course of business. The Company currently is not a party to any threatened or pending litigation. However, third parties might allege that the Company or its collaborators are infringing their patent rights or that the Company is otherwise violating their intellectual property rights. Such third parties may resort to litigation against the Company or its collaborators, which the Company has agreed to indemnify. With respect to some of these patents, the Company expects that it will be required to obtain licenses and could be required to pay license fees or royalties, or both. These licenses may not be available on acceptable terms, or at all. A costly license, or inability to obtain a necessary license, could have a material adverse effect on the Company’s financial condition, results of operations or cash flows. The Company accrues contingent liabilities when it is probable that future expenditures will be incurred and such expenditures can be reasonably estimated.
	Indemnification Agreements
	In the ordinary course of business, the Company may provide indemnifications of varying scope and terms to customers, vendors, lessors, business partners, and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements, from services to be provided by the Company, or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. Despite the fact that the Company has obtained insurance coverage for certain of these indemnification obligations, the maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company does not believe that the outcome of any claims under indemnification arrangements will have a material effect on its financial position, results of operations or cash flows, and it has not accrued any liabilities related to such obligations in its consolidated financial statements as of June 30, 2014.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
Use of Estimates	'
	Use of Estimates
	The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, management’s judgments of separate units of accounting and best estimate of selling price of those units of accounting within its revenue arrangements; the valuation of common stock for the periods prior to the completion of the Company’s initial public offering (“IPO”), valuation of warrants, Series 1 nonconvertible preferred stock and stock-based awards; the useful lives of property and equipment; and the accounting for income taxes, including uncertain tax positions and the valuation of net deferred tax assets. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates.
Revenue Recognition	'
	Revenue Recognition
	The Company’s revenue is generated primarily through collaborative research and license agreements. The terms of these agreements contain multiple deliverables, which may include (i) licenses, (ii) research and development activities, and (iii) participation in joint research and development steering committees. The terms of these agreements may include nonrefundable upfront license fees, payments for research and development activities, payments based upon the achievement of certain milestones, and royalty payments based on product sales derived from the collaboration. In all instances, revenue is recognized only when the price is fixed or determinable, persuasive evidence of an arrangement exists, delivery has occurred or the services have been rendered, collectibility of the resulting receivable is reasonably assured, and the Company has fulfilled its performance obligations under the contract.
	For multiple element agreements entered into or materially modified after October 1, 2011, the Company applies the principles included in Accounting Standards Update (“ASU”) No. 2009-13, Multiple-Deliverable Revenue Arrangements (“ASU 2009-13”) to account for revenue. Under this guidance the selling prices of deliverables under the arrangement may be derived using third-party evidence (“TPE”) or a best estimate of selling price (“BESP”), if vendor specific objective evidence (“VSOE”) is not available. The objective of BESP is to determine the price at which the Company would transact a sale if the element within the license agreement was sold on a standalone basis. Establishing BESP involves management’s judgment and considers multiple factors, including market conditions and company-specific factors including those factors contemplated in negotiating the agreements as well as internally developed models that include assumptions related to market opportunity, discounted cash flows, estimated development costs, probability of success, and the time needed to commercialize a product candidate pursuant to the license. In validating the Company’s BESP, the Company considers whether changes in key assumptions used to determine the BESP will have a significant effect on the allocation of the arrangement consideration between the multiple deliverables. Deliverables under the arrangement are separate units of accounting if (i) the delivered item has value to the customer on a standalone basis, and (ii) if the arrangement includes a general right of return relative to the delivered item, delivery or performance of the undelivered item is considered probable and substantially within the control of the Company. The arrangement consideration that is fixed or determinable at the inception of the arrangement is allocated to the separate units of accounting based on their relative selling prices. The appropriate revenue recognition model is applied to each element, and revenue is accordingly recognized as each element is delivered. The Company may exercise significant judgment in determining whether a deliverable is a separate unit of accounting.
	In determining the separate units of accounting, the Company evaluates whether the license has standalone value to the collaborator based on consideration of the relevant facts and circumstances for each arrangement. Factors considered in this determination include the research and development capabilities of the collaborator and the availability of relevant research expertise in the marketplace. In addition, the Company considers whether or not (i) the collaborator can use the license for its intended purpose without the receipt of the remaining deliverables, (ii) the value of the license is dependent on the undelivered items, and (iii) the collaborator or other vendors can provide the undelivered items.
	Under a collaborative research and license agreement, a steering committee is typically responsible for overseeing the general working relationships, determining the protocols to be followed in the research and development performed, and evaluating the results from the continued development of the product in order to determine the clinical studies to be performed. The Company evaluates whether its participation in joint research and development steering committees is a substantive obligation or whether the services are considered inconsequential or perfunctory. The Company’s participation on a steering committee is considered “participatory” and therefore accounted for as a separate element when the collaborator requires the participation of the Company to ensure all elements of an arrangement are maximized. Steering committee services that are considered participatory are combined with other research services or performance obligations required under an arrangement, if any, in determining the level of effort required in an arrangement and the period over which the Company expects to complete its aggregate performance obligations. Alternatively, the Company’s participation on a steering committee is considered “protective” and therefore not accounted for as a separate element in a case where the Company can exercise or control when to be involved at its own discretion. Factors the Company considers in determining if its participation in a joint steering committee is participating or protective include: (i) which party negotiated or requested the steering committee, (ii) how frequently the steering committee meets, (iii) whether or not there are any penalties or other recourse if the Company does not attend the steering committee meetings, (iv) which party has decision making authority on the steering committee, and (v) whether or not the collaborator has the requisite experience and expertise associated with the research and development of the licensed intellectual property.
	For agreements entered into prior to October 1, 2011, the Company accounted for the multiple elements within the agreements as a single unit of accounting and all payments received were recognized as revenue over the estimated period of performance of the entire arrangement as the Company was not able to separately recognize revenue for the elements under the provisions of previously applicable revenue recognition guidance.
	For all periods presented, whenever the Company determines that an element is delivered over a period of time, revenue is recognized using either a proportional performance model or a straight-line model over the period of performance, which is typically the research and development term. Full-time equivalents (“FTEs”) are typically used as the measure of performance. At each reporting period, the Company reassesses its cumulative measure of performance and makes appropriate adjustments, if necessary. The Company recognizes revenue using the proportional performance model whenever the Company can make reasonably reliable estimates of the level of effort required to complete its performance obligations under an arrangement. Revenue recognized under the proportional performance model at each reporting period is determined by multiplying the total expected payments under the contract (excluding royalties and payments contingent upon achievement of milestones) by the ratio of the level of effort incurred to date to the estimated total level of effort required to complete the performance obligations under the arrangement. Revenue is limited to the lesser of the cumulative amount of payments received or the cumulative amount of revenue earned, as determined using the proportional performance model as of each reporting period. Alternatively, if the Company cannot make reasonably reliable estimates the level of effort required to complete its performance obligations under an arrangement, then revenue under the arrangement is recognized on a straight-line basis over the period expected to complete the Company’s performance obligations. If and when a contingent milestone payment is earned, the additional consideration to be received is allocated to the separate units of accounting in the arrangement based on their relative selling prices at the inception of the arrangement. Revenue is limited to the lesser of the cumulative amount of payments received or the cumulative amount of revenue earned, as determined on a straight-line basis as of the period end date. If the Company cannot reasonably estimate when its performance obligation period ends, then revenue is deferred until the Company can reasonably estimate when the performance obligation period ends.
	Royalty revenue, if any, is recognized based on contractual terms when reported sales are reliably measurable and collectibility is reasonably assured, provided that there are no performance obligations then remaining. To date, none of the Company’s products have been approved, and therefore the Company has not earned any royalty revenue from product sales.
	During the three and nine months ended June 30, 2014 and 2013 the Company also generated revenue from a government contract, under which the Company is reimbursed for certain allowable costs for the funded project. Revenue from the government contract is recognized when the related service is performed. The related costs incurred by the Company under the government contract are included in research and development expenses in the statements of operations.
	Amounts received prior to satisfying all revenue recognition criteria are recorded as deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized as revenue within the next twelve months of the consolidated balance sheet date are classified as long-term deferred revenue.
	In the event that a collaborative research and license agreement is terminated and the Company then has no further performance obligations, the Company recognizes as revenue any amounts that had not previously been recorded as revenue but were classified as deferred revenue at the date of such termination.
Recently Issued Accounting Pronouncements	'
	Recently Issued Accounting Pronouncements
	In May, 2014, the Financial Accounting Standards Board issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the Company expects to receive for those goods or services. The new standard will be effective for the Company on October 1, 2017. The Company is currently evaluating the potential impact that Topic 606 may have on its financial position and results of operations.

Fair_Value_of_Financial_Assets1

Fair Value of Financial Assets and Liabilities (Tables)	9 Months Ended
	Jun. 30, 2014
Fair Value Disclosures [Abstract]	'
Financial Assets and Liabilities that were Subject to Fair Value Measurement on Recurring Basis	'
	The following tables present information about the Company’s financial assets and liabilities that were subject to fair value measurement on a recurring basis as of June 30, 2014 and September 30, 2013 and indicate the fair value hierarchy of the valuation inputs utilized to determine such fair value:
		Fair Value Measurements as of June 30, 2014 Using:
		Level   1			Level   2		Level   3		Total
	Assets:
	Cash equivalents	$	21,972		$	—	$	—	$	21,972
	Commercial paper		—			11,840		—		11,840
	Corporate bonds		—			93,860		—		93,860
	U.S. Agency bonds		—			5,513		—		5,513
		$	21,972		$	111,213	$	—	$	133,185
	Liabilities:
	Warrant liability	$	—		$	—	$	1,675	$	1,675
	Series 1 nonconvertible preferred stock		—			—		213		213
		$	—		$	—	$	1,888	$	1,888
		Fair Value Measurements as of September 30, 2013  Using:
		Level 1			Level 2		Level 3		Total
	Assets:
	Cash equivalents	$	7,517		$	—	$	—	$	7,517
	U.S. Treasury notes		1,005			—		—		1,005
	Commercial paper		—			10,596		—		10,596
	Corporate bonds		—			84,755		—		84,755
	U.S. Agency bonds		—			3,518		—		3,518
	Certificate of deposit		—			3,450		—		3,450
		$	8,522		$	102,319	$	—	$	110,841
	Liabilities:
	Warrant liability	$	—		$	—	$	1,620	$	1,620
		$	—		$	—	$	1,620	$	1,620
Fair Value Measurements of the Company's Warrant Liability and Series 1 Nonconvertible Preferred Stock	'
	The recurring Level 3 fair value measurements of the Company’s warrant liability and Series 1 nonconvertible preferred stock using probability-weighted discounted cash flow include the following significant unobservable inputs:
		Unobservable Input		Range
				(Weighted
				Average)
	Warrant liability and Series 1 nonconvertible preferred stock	Probabilities of payout		70%–90%
		Periods in which payout is expected to occur		2015–2016
		Discount rate		4.25%
Rollforward of Aggregate Fair Values of Warrants and Series 1 Nonconvertible Preferred Stock Outstanding	'
	The following table provides a rollforward of the aggregate fair values of the Company’s warrants for the purchase of Series 1 nonconvertible preferred stock and the outstanding Series 1 nonconvertible preferred stock for which fair value is determined by Level 3 inputs:
		Warrants			Series 1
					nonconvertible
					preferred
					stock
	Balance, September 30, 2013	$	1,620		$	—
	Warrants exercised		(206	)		206
	Increase in fair value		261			7
	Balance, June 30, 2014	$	1,675		$	213

Marketable_Securities_Tables

Marketable Securities (Tables)	9 Months Ended
	Jun. 30, 2014
Investments Debt And Equity Securities [Abstract]	'
Fair Value of Available-for-Sale Marketable Securities by Type of Security	'
	As of June 30, 2014 and September 30, 2013, the fair value of available-for-sale marketable securities by type of security was as follows:
		June 30, 2014
		Amortized Cost		Gross Unrealized		Gross Unrealized			Fair Value
				Gains		Losses
	Commercial paper	$	11,840	$	—	$	—		$	11,840
	Corporate bonds		93,861		44		(45	)		93,860
	U.S. Agency bonds		5,516		—		(3	)		5,513
		$	111,217	$	44	$	(48	)	$	111,213
		September 30, 2013
		Amortized Cost		Gross Unrealized		Gross Unrealized			Fair Value
				Gains		Losses
	Commercial paper	$	10,596	$	—	$	—		$	10,596
	Corporate bonds		84,757		23		(25	)		84,755
	U.S. Agency bonds		3,519		—		(1	)		3,518
	Certificate of deposit		3,450		—		—			3,450
	U.S. Treasury notes		1,004		1		—			1,005
		$	103,326	$	24	$	(26	)	$	103,324

Accrued_Expenses_and_Other_Lon1

Accrued Expenses and Other Long-Term Liabilities (Tables)	9 Months Ended
	Jun. 30, 2014
Payables And Accruals [Abstract]	'
Accrued Expenses (Current) and Other Long-Term Liabilities	'
	Accrued expenses (current) and other long-term liabilities consisted of the following as of June 30, 2014 and September 30, 2013:
		June 30,		September 30,
		2014		2013
	Accrued expenses:
	Accrued payroll and related expenses	$	953	$	1,041
	Accrued preclinical and clinical expenses		623		127
	Accrued vendor manufacturing		477		989
	Accrued professional fees		336		378
	Present value of accrued third-party license fees		247		240
	Accrued other		348		260
		$	2,984	$	3,035
	Other long-term liabilities:
	Present value of accrued third-party license fees	$	190	$	127
	Accrued rent expense		147		184
	Asset retirement obligation		68		48
		$	405	$	359

StockBased_Awards_Tables

Stock-Based Awards (Tables)	9 Months Ended
	Jun. 30, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Data Used to Determine Value of Stock Option Grants, Presented on Weighted Average Basis	'
	The relevant data used to determine the value of the stock option grants is as follows, presented on a weighted average basis:
		Three Months Ended June 30,						Nine Months Ended June 30,
		2014			2013			2014			2013
	Risk-free interest rate		1.93	%		1.16	%		1.89	%		1.03	%
	Expected term (in years)		6.1			6			6.06			6.09
	Expected volatility		76	%		77	%		75	%		73	%
	Expected dividend yield		0	%		0	%		0	%		0	%
Stock Option Activity	'
	The following table summarizes stock option activity during the nine months ended June 30, 2014:
		Shares			Weighted			Weighted			Aggregate
		Issuable			Average			Average			Intrinsic
		Under			Exercise			Remaining			Value
		Options			Price			Contractual
								Term
					(in years)
	Outstanding as of September 30, 2013		1,583,031		$	5.15			5		$	28,133
	Granted		483,570			29.73
	Exercised		(650,939	)		1.56
	Forfeited		(9,343	)		14
	Expired		(465	)		0.73
	Outstanding as of June 30, 2014		1,405,854		$	15.21			7.4		$	38,818
	Options vested and expected to vest as of June 30, 2014		1,221,172		$	15.2			7.2		$	34,028
	Options exercisable as of June 30, 2014		676,867		$	6.42			5.6		$	24,960
Stock-Based Compensation Expense	'
	The Company recorded stock-based compensation expense for the three and nine months ended June 30, 2014 and 2013 in the following expense categories:
		Three Months Ended						Nine Months Ended
		June 30,						June 30,
		2014			2013			2014			2013
	Research and development	$	196		$	107		$	562		$	286
	General and administrative		580			132			1,325			491
		$	776		$	239		$	1,887		$	777

Net_Income_Loss_Per_Share_Tabl

Net Income (Loss) Per Share (Tables)	9 Months Ended
	Jun. 30, 2014
Earnings Per Share [Abstract]	'
Basic and Diluted Net Income (Loss) Per Share Attributable to Common Stockholders	'
	Basic and diluted net income (loss) per share attributable to common stockholders was calculated as follows for the three and nine months ended June 30, 2014 and 2013, respectively:
		Three Months Ended					Nine Months Ended
		June 30,					June 30,
		2014		2013			2014		2013
	Basic net income (loss) per share attributable to common stockholders:
	Numerator:
	Net income (loss)	$	50,053	$	(4,138	)	$	39,480	$	14,070
	Accretion of redeemable convertible preferred stock to redemption value		—		—			—		(2,526	)
	Net income attributable to participating securities		—		—			—		(13,670	)
	Net income (loss) attributable to common stockholders	$	50,053	$	(4,138	)	$	39,480	$	(2,126	)
	Denominator:
	Weighted average common shares outstanding—basic		18,528,833		17,819,813			18,275,831		7,052,989
	Net income (loss) per share attributable to common stockholders—basic	$	2.7	$	(0.23	)	$	2.16	$	(0.30	)
	Diluted net income (loss) per share attributable to common stockholders:
	Numerator:
	Net income (loss)	$	50,053	$	(4,138	)	$	39,480	$	14,070
	Accretion of redeemable convertible preferred stock to redemption value		—		—			—		(2,526	)
	Net income attributable to participating securities		—		—			—		(13,670	)
	Net income (loss) attributable to common stockholders—diluted	$	50,053	$	(4,138	)	$	39,480	$	(2,126	)
	Denominator:
	Weighted average common shares outstanding—basic		18,528,833		17,819,813			18,275,831		7,052,989
	Dilutive effect of common stock equivalents		674,437		—			892,537		—
	Weighted average common shares outstanding—diluted		19,203,270		17,819,813			19,168,368		7,052,989
	Net income (loss) per share attributable to common stockholders—diluted	$	2.61	$	(0.23	)	$	2.06	$	(0.30	)

Fair_Value_of_Financial_Assets2

Fair Value of Financial Assets and Liabilities - Financial Assets and Liabilities that were Subject to Fair Value Measurement on Recurring Basis (Detail) (USD $)	Jun. 30, 2014	Sep. 30, 2013
In Thousands, unless otherwise specified
Assets:	'	'
Cash equivalents	$21,972	$7,517
Available for sale securities, fair value	111,213	103,324
Assets, Fair Value Disclosure, Total	133,185	110,841
Liabilities:	'	'
Warrant liability	1,675	1,620
Liabilities, Fair Value Disclosure, Total	1,888	1,620
U.S. Treasury Notes [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	'	1,005
Commercial Paper [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	11,840	10,596
Corporate Bonds [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	93,860	84,755
U.S. Agency Bonds [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	5,513	3,518
Certificate of Deposit [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	'	3,450
Series 1 Nonconvertible Preferred Stock [Member]	'	'
Liabilities:	'	'
Warrant liability	1,675	1,620
Series 1 nonconvertible preferred stock	213	'
Level 1 [Member]	'	'
Assets:	'	'
Cash equivalents	21,972	7,517
Assets, Fair Value Disclosure, Total	21,972	8,522
Liabilities:	'	'
Warrant liability	'	'
Liabilities, Fair Value Disclosure, Total	'	'
Level 1 [Member] | U.S. Treasury Notes [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	'	1,005
Level 1 [Member] | Commercial Paper [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	'	'
Level 1 [Member] | Corporate Bonds [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	'	'
Level 1 [Member] | U.S. Agency Bonds [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	'	'
Level 1 [Member] | Certificate of Deposit [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	'	'
Level 1 [Member] | Series 1 Nonconvertible Preferred Stock [Member]	'	'
Liabilities:	'	'
Series 1 nonconvertible preferred stock	'	'
Level 2 [Member]	'	'
Assets:	'	'
Cash equivalents	'	'
Assets, Fair Value Disclosure, Total	111,213	102,319
Liabilities:	'	'
Warrant liability	'	'
Liabilities, Fair Value Disclosure, Total	'	'
Level 2 [Member] | U.S. Treasury Notes [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	'	'
Level 2 [Member] | Commercial Paper [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	11,840	10,596
Level 2 [Member] | Corporate Bonds [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	93,860	84,755
Level 2 [Member] | U.S. Agency Bonds [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	5,513	3,518
Level 2 [Member] | Certificate of Deposit [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	'	3,450
Level 2 [Member] | Series 1 Nonconvertible Preferred Stock [Member]	'	'
Liabilities:	'	'
Series 1 nonconvertible preferred stock	'	'
Level 3 [Member]	'	'
Assets:	'	'
Cash equivalents	'	'
Assets, Fair Value Disclosure, Total	'	'
Liabilities:	'	'
Warrant liability	1,675	1,620
Liabilities, Fair Value Disclosure, Total	1,888	1,620
Level 3 [Member] | U.S. Treasury Notes [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	'	'
Level 3 [Member] | Commercial Paper [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	'	'
Level 3 [Member] | Corporate Bonds [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	'	'
Level 3 [Member] | U.S. Agency Bonds [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	'	'
Level 3 [Member] | Certificate of Deposit [Member]	'	'
Assets:	'	'
Available for sale securities, fair value	'	'
Level 3 [Member] | Series 1 Nonconvertible Preferred Stock [Member]	'	'
Liabilities:	'	'
Series 1 nonconvertible preferred stock	$213	'

Fair_Value_of_Financial_Assets3

Fair Value of Financial Assets and Liabilities - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Sep. 30, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Transfers between Level 1, Level 2 and Level 3	$0	$0	$0	$0	'
Fair value of warrants	1,675	'	1,675	'	1,620
Series 1 Nonconvertible Preferred Stock [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Fair value of warrants	1,675	'	1,675	'	1,620
Fair value of Series 1 nonconvertible preferred stock	$213	'	$213	'	'

Fair_Value_of_Financial_Assets4

Fair Value of Financial Assets and Liabilities - Fair Value Measurements of the Company's Warrant Liability and Series 1 Nonconvertible Preferred Stock (Detail) (Warrant Liability [Member], Series 1 Nonconvertible Preferred Stock [Member])	9 Months Ended
	Jun. 30, 2014
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]	'
Discount rate	4.25%
Minimum [Member]	'
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]	'
Probabilities of payout	70.00%
Periods in which payout is expected to occur	'2015
Maximum [Member]	'
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]	'
Probabilities of payout	90.00%
Periods in which payout is expected to occur	'2016

Fair_Value_of_Financial_Assets5

Fair Value of Financial Assets and Liabilities - Rollforward of Aggregate Fair Values of Warrants and Series 1 Nonconvertible Preferred Stock Outstanding (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014
Warrant Liability [Member]	'
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'
Beginning Balance	$1,620
Warrants exercised	-206
Increase in fair value	261
Ending Balance	1,675
Series 1 Nonconvertible Preferred Stock [Member]	'
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'
Beginning Balance	'
Warrants exercised	206
Increase in fair value	7
Ending Balance	$213

Marketable_Securities_Fair_Val

Marketable Securities - Fair Value of Available-for-Sale Marketable Securities by Type of Security (Detail) (USD $)	Jun. 30, 2014	Sep. 30, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	$111,217	$103,326
Gross Unrealized Gains	44	24
Gross Unrealized Losses	-48	-26
Fair Value	111,213	103,324
Commercial Paper [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	11,840	10,596
Gross Unrealized Gains	'	'
Gross Unrealized Losses	'	'
Fair Value	11,840	10,596
Corporate Bonds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	93,861	84,757
Gross Unrealized Gains	44	23
Gross Unrealized Losses	-45	-25
Fair Value	93,860	84,755
U.S. Agency Bonds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	5,516	3,519
Gross Unrealized Gains	'	'
Gross Unrealized Losses	-3	-1
Fair Value	5,513	3,518
Certificate of Deposit [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	'	3,450
Gross Unrealized Gains	'	'
Gross Unrealized Losses	'	'
Fair Value	'	3,450
U.S. Treasury Notes [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	'	1,004
Gross Unrealized Gains	'	1
Gross Unrealized Losses	'	'
Fair Value	'	$1,005

Marketable_Securities_Addition

Marketable Securities - Additional Information (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014
Schedule of Available-for-sale Securities [Line Items]	'
Marketable securities maturing within two years, aggregate fair value	41,700
Short Term Marketable Securities [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Maturity period of the marketable securities	'Within one year
Corporate Bond Securities [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Maturity period of the marketable securities	'Within three years

Accrued_Expenses_and_Other_Lon2

Accrued Expenses and Other Long-Term Liabilities - Accrued Expenses (Current) and Other Long-Term Liabilities (Detail) (USD $)	Jun. 30, 2014	Sep. 30, 2013
In Thousands, unless otherwise specified
Accrued expenses:	'	'
Accrued payroll and related expenses	$953	$1,041
Accrued preclinical and clinical expenses	623	127
Accrued vendor manufacturing	477	989
Accrued professional fees	336	378
Present value of accrued third-party license fees	247	240
Accrued other	348	260
Accrued expenses	2,984	3,035
Other long-term liabilities:	'	'
Present value of accrued third-party license fees	190	127
Accrued rent expense	147	184
Asset retirement obligation	68	48
Other long-term liabilities	$405	$359

Collaboration_Agreements_Addit

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

3 Months Ended

1 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

0 Months Ended

1 Months Ended

0 Months Ended

1 Months Ended

0 Months Ended

3 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

0 Months Ended

In Thousands, unless otherwise specified

Jun. 30, 2014

Jun. 30, 2011

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2012

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Feb. 16, 2012

Jan. 31, 2013

Feb. 16, 2012

Feb. 16, 2012

Mar. 31, 2013

Feb. 16, 2012

Feb. 16, 2012

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Aug. 31, 2013

Sep. 30, 2011

Jun. 30, 2014

Sep. 30, 2011

Sep. 30, 2011

AbbVie [Member]

AbbVie [Member]

AbbVie [Member]

AbbVie [Member]

AbbVie [Member]

AbbVie [Member]

Novartis [Member]

Novartis [Member]

Novartis [Member]

Novartis [Member]

Novartis [Member]

Novartis [Member]

Novartis [Member]

Novartis [Member]

Novartis [Member]

Novartis [Member]

Novartis [Member]

National Institutes of Health, National Institute of Allergy and Infectious Diseases [Member]

National Institutes of Health, National Institute of Allergy and Infectious Diseases [Member]

National Institutes of Health, National Institute of Allergy and Infectious Diseases [Member]

National Institutes of Health, National Institute of Allergy and Infectious Diseases [Member]

National Institutes of Health, National Institute of Allergy and Infectious Diseases [Member]

National Institutes of Health, National Institute of Allergy and Infectious Diseases [Member]

National Institutes of Health, National Institute of Allergy and Infectious Diseases [Member]

National Institutes of Health, National Institute of Allergy and Infectious Diseases [Member]

National Institutes of Health, National Institute of Allergy and Infectious Diseases [Member]

Commercial Milestone Payments [Member]

Commercial Milestone Payments [Member]

Milestone Payments [Member]

Quality Assurance and Testing [Member]

Phase 1 Clinical Trial [Member]

Phase 2 Clinical Trial [Member]

Research Contracts [Member]

Research Contracts [Member]

Maximum [Member]

Maximum [Member]

Initial [Member]

Initial [Member]

Maximum [Member]

Maximum [Member]

Additional Funding Agreement Terms [Member]

Phase 3 Clinical Trial [Member]

Research Contracts [Member]

Renewals

Initial [Member]

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

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Collaboration agreement date

'

'

'

'2006-11-27

'

'

'

'

'

'2012-02-16

'

'

'

'

'

'

'

'

'

'

'2011-09-30

'

'

'

'

'

'

Collaboration agreement tiered royalty description

'

'

'

'From the low double digits up to twenty percent, or on a blended basis from the low double digits up to the high teens, on net sales

'

'

'

'

'

'From the low double digits up to the high teens on net product sales

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Upfront license payments, research funding, and milestone payments

'

$92,450

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Milestone revenue payments received

40,000

'

40,000

'

'

'

15,000

0

'

0

'

'

11,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Expected proceed from milestone payment

'

'

'

'

155,000

80,000

'

'

'

'

'

'

'

15,000

'

'

406,000

'

'

'

'

'

'

'

'

'

'

Expected nonrefundable upfront fee and reimbursement expense

'

'

'

'

'

'

'

'

'

'

'

34,442

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Funding related to research and development

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,800

23,500

'

23,500

'

9,200

'

'

'

'

Research funding period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'1 year

'

'

'

'

'

'

'

'

'

'

'

'

Additional research funding period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'6 months

'

'

'

'

'

'

'

'

'

'

'

Delivery of license and the research services revenue

'

'

'

'

'

'

'

'

473

'

12,350

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Awarded contract for development, amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

14,300

'

42,700

42,700

Awarded contract for development, contract period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'30 months

'

'5 years

'

Expiration date

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

30-Mar-14

'

'

Awarded contract for development, number of extension option

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

6

'

Extended expiration date

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'September 30, 2016

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'

'

'

'

'

Revenue from grants

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$2,051

$1,176

$5,104

$3,354

'

'

'

'

'

Warrants_to_Purchase_Series_1_1

Warrants to Purchase Series 1 Nonconvertible Preferred Stock and Series 1 Nonconvertible Preferred Stock - Additional Information (Detail) (USD $)	0 Months Ended	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Feb. 05, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Sep. 30, 2013	Nov. 30, 2010
Class of Stock [Line Items]	'	'	'	'	'	'	'
(Income) expense from change in fair value of outstanding warrants	'	$65	$17	$268	($217)	'	'
Fair value of warrants	'	1,675	'	1,675	'	1,620	'
Series 1 Nonconvertible Preferred Stock [Member]	'	'	'	'	'	'	'
Class of Stock [Line Items]	'	'	'	'	'	'	'
Number of shares issuable upon exercise of the warrants	'	'	'	'	'	'	1,999,989
Warrant expiration date	'	'	'	4-Oct-17	'	'	'
Warrant exercised	225,408	'	'	'	'	'	'
Warrants issuance	223,153	'	'	'	'	'	'
Fair value of the Series 1 nonconvertible preferred stock	'	213	'	213	'	'	'
(Income) expense from change in fair value of outstanding warrants	'	65	17	268	-217	'	'
Fair value of warrants	'	$1,675	'	$1,675	'	$1,620	'

StockBased_Awards_Additional_I

Stock-Based Awards - Additional Information (Detail) (USD $)	9 Months Ended		0 Months Ended		1 Months Ended	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Sep. 30, 2013	Jan. 17, 2013	Jun. 30, 2014	Mar. 31, 2013	Jun. 30, 2014
			2012 Equity Incentive Plan [Member]	2012 Equity Incentive Plan [Member]	2012 Equity Incentive Plan [Member]	2012 Equity Incentive Plan [Member]
					Executive Officer [Member]	Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'
Common stock shares authorized	'	'	348,355	'	'	'
Percentage of potential common stock shares to be issued	'	'	3.00%	'	'	'
Potential number of common stock shares to be issued	'	'	2,088,167	'	'	'
Shares available for future grant	'	'	'	410,380	'	'
Options granted to executives	483,570	'	'	'	167,052	'
Fair value of options at the grant date	'	'	'	'	$2,479	'
Stock based compensation, expenses	'	'	'	'	'	206
Common stock reserved	'	185,614	'	'	'	'
Shares issued under the ESPP	0	'	'	'	'	'
Aggregate of unrecognized stock-based compensation cost	$9,067	'	'	'	'	'
Weighted average recognition period	'3 years	'	'	'	'	'

StockBased_Awards_Data_Used_to

Stock-Based Awards - Data Used to Determine Value of Stock Option Grants, Presented on Weighted Average Basis (Detail)	3 Months Ended		9 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'	'	'
Risk-free interest rate	1.93%	1.16%	1.89%	1.03%
Expected term (in years)	'6 years 1 month 6 days	'6 years	'6 years 22 days	'6 years 1 month 2 days
Expected volatility	76.00%	77.00%	75.00%	73.00%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

StockBased_Awards_Stock_Option

Stock-Based Awards - Stock Option Activity (Detail) (USD $)	0 Months Ended	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2014
Shares Issuable Under Options	'	'
Outstanding as of beginning of period	1,583,031	1,583,031
Granted	'	483,570
Exercised	'	-650,939
Forfeited	'	-9,343
Expired	'	-465
Outstanding as of end of period	'	1,405,854
Options vested and expected to vest as of end of period	'	1,221,172
Options exercisable as of end of period	'	676,867
Weighted Average Exercise Price	'	'
Outstanding as of beginning of period	$5.15	$5.15
Granted	'	$29.73
Exercised	'	$1.56
Forfeited	'	$14
Expired	'	$0.73
Outstanding as of ending balance	'	$15.21
Options vested and expected to vest as of end of period	'	$15.20
Options exercisable as of end of period	'	$6.42
Weighted Average Remaining Contractual Term (In years)	'	'
Outstanding as of end of period	'5 years	'7 years 4 months 24 days
Options vested and expected to vest as of end period	'	'7 years 2 months 12 days
Options exercisable as of end of period	'	'5 years 7 months 6 days
Aggregate Intrinsic Value	'	'
Outstanding as of beginning of period	$28,133	$28,133
Outstanding as of end of period	'	38,818
Options vested and expected to vest as of end of period	'	34,028
Options exercisable as of end of period	'	$24,960

StockBased_Awards_StockBased_C

Stock-Based Awards - Stock-Based Compensation Expense (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation expense	$776	$239	$1,887	$777
Research and Development [Member]	'	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation expense	196	107	562	286
General and Administrative [Member]	'	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation expense	$580	$132	$1,325	$491

Net_Income_Loss_Per_Share_Basi

Net Income (Loss) Per Share - Basic and Diluted Net Income (Loss) Per Share Attributable to Common Stockholders (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Basic net income (loss) per share attributable to common stockholders:	'	'	'	'
Net income (loss)	$50,053	($4,138)	$39,480	$14,070
Accretion of redeemable convertible preferred stock to redemption value	'	'	'	-2,526
Net income attributable to participating securities	'	'	'	-13,670
Net income (loss) attributable to common stockholders	50,053	-4,138	39,480	-2,126
Weighted average common shares outstanding-basic	18,528,833	17,819,813	18,275,831	7,052,989
Net income (loss) per share attributable to common stockholders-basic	$2.70	($0.23)	$2.16	($0.30)
Diluted net income (loss) per share attributable to common stockholders:	'	'	'	'
Net income (loss)	50,053	-4,138	39,480	14,070
Accretion of redeemable convertible preferred stock to redemption value	'	'	'	-2,526
Net income attributable to participating securities	'	'	'	-13,670
Net income (loss) attributable to common stockholders-diluted	$50,053	($4,138)	$39,480	($2,126)
Weighted average common shares outstanding-basic	18,528,833	17,819,813	18,275,831	7,052,989
Dilutive effect of common stock equivalents	674,437	'	892,537	'
Weighted average common shares outstanding-diluted	19,203,270	17,819,813	19,168,368	7,052,989
Net income (loss) per share attributable to common stockholders-diluted	$2.61	($0.23)	$2.06	($0.30)

Net_Income_Loss_Per_Share_Addi

Net Income (Loss) Per Share - Additional Information (Detail) (Stock Option [Member])	3 Months Ended		9 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Stock Option [Member]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Shares excluded from the computation of diluted net income per share	433,535	1,525,952	300,428	1,685,921

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2013
Income Tax Disclosure [Abstract]	'	'	'
Income tax benefit	$15,122	$15,122	'
Milestone payments	40,000	'	'
Valuation allowance	22,892	22,892	'
Change in estimate regarding future years' income	'	15,333	'
Released to income as deferred tax assets	$7,559	$7,559	'
Effective income tax rate	'	80.70%	0.00%
Federal Statutory income tax rate	'	34.00%	34.00%

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Sep. 30, 2013
Commitments And Contingencies [Line Items]	'	'	'	'	'
Rent expense	$237	$237	$711	$711	'
Office lease expiration period	'	'	'September 2018	'	'
Outstanding letter of credit	436	'	436	'	'
Restricted cash	436	'	436	'	436
Maintenance fees	'	'	105	'	'
One-time fee	'	'	50	'	'
License agreement, recorded liability	437	'	437	'	'
Company's obligation to pay	'	'	5,000	'	'
Fiscal Year 2014 [Member]	'	'	'	'	'
Commitments And Contingencies [Line Items]	'	'	'	'	'
License expense	'	'	250	'	'
Fiscal Year 2015 [Member]	'	'	'	'	'
Commitments And Contingencies [Line Items]	'	'	'	'	'
License expense	'	'	200	'	'
Accrued Expenses [Member]	'	'	'	'	'
Commitments And Contingencies [Line Items]	'	'	'	'	'
License agreement, recorded liability	247	'	247	'	'
Other Long-Term Liabilities [Member]	'	'	'	'	'
Commitments And Contingencies [Line Items]	'	'	'	'	'
License agreement, recorded liability	$190	'	$190	'	'