Document And Entity Information	3 Months Ended
Document And Entity Information	Mar. 31, 2015	May 11, 2015
Document And Entity Information [Abstract]
Entity Registrant Name	Xenon Pharmaceuticals Inc.
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		14,228,536
Amendment Flag	false
Entity Central Index Key	0001582313
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
Document Period End Date	Mar. 31, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1

Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 65,917	$ 72,026
Marketable securities	9,464	12,015
Accounts receivable	1,205	215
Prepaid expenses and other current assets	464	686
Total current assets	77,050	84,942
Property, plant and equipment, net	2,353	2,476
Total assets	79,403	87,418
Current liabilities:
Accounts payable and accrued expenses (note 7)	1,530	2,664
Deferred revenue	8,724	11,622
Total current liabilities	10,254	14,286
Deferred revenue, less current portion		157
Deferred tenant inducements	180	196
Total liabilities	10,434	14,639
Shareholders’ equity:
Common shares, without par value; unlimited shares authorized; issued and outstanding: 14,222,275 (December 31, 2014 - 14,181,333)	147,508	147,157
Additional paid-in capital	30,450	30,346
Accumulated deficit	(107,999)	(103,734)
Accumulated other comprehensive loss	(990)	(990)
Shareholders’ equity	68,969	72,779
Total liabilities and shareholders’ equity	79,403	87,418
Commitments and contingencies (note 10)

Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Common shares, Par Value (in Dollars per share)	$ 0	$ 0
Common shares, Issued	14,222,275	14,181,333
Common shares, Outstanding	14,222,275	14,181,333

Statements of Operations and Comprehensive Income (Loss) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Revenue:
Collaboration revenue (note 9)	$ 4,010	$ 5,001
Operating expenses:
Research and development	3,427	2,533
General and administrative	1,789	1,436
Total operating expenses	5,216	3,969
Income (loss) from operations	(1,206)	1,032
Other income (expense):
Interest income	152	141
Foreign exchange gain (loss)	(3,171)	200
Net income (loss)	(4,225)	1,373
Net income attributable to participating securities		1,373
Net loss attributable to common shareholders	(4,225)
Net loss per common share:
Basic and diluted	$ (0.30)
Weighted-average shares outstanding:
Basic and diluted	14,212,579	1,345,312
Other comprehensive income (loss):
Foreign currency translation adjustment		(909)
Comprehensive income (loss)	$ (4,225)	$ 464

Statement of Shareholders' Equity (Deficit) (USD $)
In Thousands, except Share data

Total

Preferred Stock [Member]

Series A Preferred Stock [Member]

Preferred Stock [Member]

Series B Preferred Stock [Member]

Preferred Stock [Member]

Series E Preferred Stock [Member]

Common Stock [Member]

Additional Paid-in Capital [Member]

Retained Earnings [Member]

Accumulated Other Comprehensive Income (Loss) [Member]

Balance at Dec. 31, 2013

$ (78,372)

$ 2,939

$ 8,683

$ 90,866

$ 6,147

$ 29,722

$ (116,752)

$ 2,511

Balance (in Shares) at Dec. 31, 2013

1,151,468

994,885

4,322,126

1,344,627

Net income (loss)

13,018

Conversion of Series A, B and E convertible preferred shares

102,488

(2,939)

(8,683)

(90,866)

102,488

Conversion of series A, B and E convertible preferred shares (in Shares)

(1,151,468)

(994,885)

(4,322,126)

7,725,924

Issuance of common shares, net of issuance costs

38,373

Issuance of common shares, net of issuance costs (in Shares)

5,095,000

Foreign currency translation adjustment

(3,501)

Stock option compensation expense

760

Issuance of common shares on conversion of subscription rights

124

(124)

Issuance of common shares on conversion of subscription rights (in Shares)

13,365

Issued pursuant to exercise of stock options

(12)

Issued pursuant to exercise of stock options (in Shares)

2,417

Balance at Dec. 31, 2014

72,779

147,157

30,346

(103,734)

(990)

Balance (in Shares) at Dec. 31, 2014

14,181,333

Net income (loss)

(4,225)

Stock option compensation expense

288

Issued pursuant to exercise of stock options

127

351

(184)

(40)

Issued pursuant to exercise of stock options (in Shares)

44,656

^[1]

40,942

Balance at Mar. 31, 2015

$ 68,969

$ 147,508

$ 30,450

$ (107,999)

$ (990)

Balance (in Shares) at Mar. 31, 2015

14,222,275

[1]	During the three months ended March 31, 2015, 26,910 stock options were exercised for the same number of common shares for cash. In the same period, the Company issued 14,032 common shares for the cashless exercise of 17,746 stock options.

Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Operating activities:
Net income (loss)	$ (4,225)	$ 1,373
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization	207	175
Stock-based compensation	288	186
Deferred tenant inducements	(16)	(17)
Unrealized foreign exchange loss	3,140	37
Changes in operating assets and liabilities:
Accounts receivable	(996)	2
Prepaid expenses, and other current assets	220	29
Accounts payable and accrued expenses	(1,110)	(265)
Deferred revenue	(3,055)	(2,362)
Net cash used in operating activities	(5,547)	(842)
Investing activities:
Purchases of property, plant and equipment	(84)	(480)
Purchase of marketable securities		(2,578)
Proceeds from marketable securities	1,575	2,720
Net cash provided by (used in) investing activities	1,491	(338)
Financing activities:
Deferred financing fees		(398)
Proceeds from issuance of common shares	127	5
Net cash provided by (used in) financing activities	127	(393)
Effect of exchange rate changes on cash and cash equivalents	(2,180)	(1,430)
Decrease in cash and cash equivalents	(6,109)	(3,003)
Cash and cash equivalents, beginning of period	72,026	37,950
Cash and cash equivalents, end of period	65,917	34,947
Supplemental disclosures:
Interest received	121	125
Supplemental disclosures of non-cash transactions:
Issuance of common shares on conversion of subscription rights		14
Fair value of options exercised on a cashless basis	$ 69

Nature of the Business

3 Months Ended

Mar. 31, 2015

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Nature of the business

1.	Nature of the business:

Xenon Pharmaceuticals Inc. (the “Company”), incorporated in 1996 under the British Columbia Business Corporations Act and continued federally in 2000 under the Canada Business Corporation Act, is a clinical-stage biopharmaceutical company discovering and developing a pipeline of differentiated therapeutics for orphan indications that it intends to commercialize on its own, and for larger market indications that it intends to partner with global pharmaceutical companies.

On October 1, 2014, the Company effected a 1 for 4.86 reverse share split of its common and Series A, B and E redeemable convertible preferred shares. At the time of the consolidation, there were no outstanding Series C and D preferred shares and therefore such series were not included in the consolidation. Accordingly, (i) every 4.86 common shares were combined into one common share, (ii) every 4.86 redeemable Series A, B and E convertible preferred shares were combined into one redeemable convertible preferred share, (iii) the number of common shares into which each outstanding subscription right was exchangeable into common shares were proportionately decreased on a 1 for 4.86 basis, (iv) the number of common shares into which each outstanding option to purchase common shares was exercisable were proportionately decreased on a 1 for 4.86 basis, and (v) the exercise price for each such outstanding option to purchase common shares was proportionately increased on a 1 for 4.86 basis. All of the share numbers, share prices, and exercise prices prior to October 1, 2014 have been adjusted, on a retroactive basis, to reflect this 1 for 4.86 reverse share split.

On November 10, 2014, the Company completed an initial public offering (“IPO”) of 4,600,000 of its common shares at a price to the public of $9.00 per share. On November 10, 2014, the Company also completed a private placement, in which the Company issued 495,000 of its common shares to an affiliate of Genentech, Inc. (“Genentech”) at a price of $9.00 per share. Immediately prior to the closing of the IPO, all outstanding convertible preferred shares were converted into 7,725,924 common shares and 10,201 outstanding subscription rights were converted into 10,201 common shares. Following the IPO, there were no preferred shares or subscription rights outstanding.

- Definition

The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.

+ References+ Details

Basis of Presentation

3 Months Ended

Mar. 31, 2015

Accounting Policies [Abstract]

Basis of presentation

2.	Basis of presentation:

These financial statements are presented in U.S. dollars.

The accompanying unaudited interim financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) and pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”) for interim financial information. Accordingly, these financial statements do not include all of the information and footnotes required for complete financial statements and should be read in conjunction with the audited financial statements and notes for the year ended December 31, 2014 and included in the Company’s 2014 Annual Report on Form 10-K filed with the SEC on March 12, 2015.

These unaudited interim financial statements reflect all adjustments, consisting of normal recurring adjustments, which, in the opinion of management, are necessary for a fair presentation of results for the interim periods presented. The results of operations for the three month periods ended March 31, 2015 and 2014 are not necessarily indicative of results that can be expected for a full year. These unaudited interim financial statements follow the same significant accounting policies as those described in the notes to the audited financial statements of the Company included in the Company’s 2014 Annual Report on Form 10-K for the year ended December 31, 2014, with the exception of the change in functional currency described in note 3.

Changes in Significant Accounting Policies

3 Months Ended

Mar. 31, 2015

Accounting Changes And Error Corrections [Abstract]

Changes in significant accounting policies

3.	Changes in significant accounting policies:

The Company’s reporting currency is the U.S. dollar. The functional currency of the Company changed to U.S. dollars from Canadian dollars on January 1, 2015 based on management’s analysis of the changes in the primary economic environment in which the Company operates. The change in functional currency is accounted for prospectively from January 1, 2015 and prior year financial statements have not been restated for the change in functional currency. Past translation gains and losses from the application of the U.S. dollar as the reporting currency while the Canadian dollar was the functional currency are included as part of the cumulative foreign currency translation adjustment, which is reported as a component of shareholders’ equity under accumulated other comprehensive loss.

For periods commencing January 1, 2015, monetary assets and liabilities denominated in foreign currencies are translated into U.S. dollars using exchange rates in effect at the balance sheet date. Opening balances related to non-monetary assets and liabilities are based on prior period translated amounts, and nonmonetary assets and nonmonetary liabilities incurred after January 1, 2015 are translated at the approximate exchange rate prevailing at the date of the transaction. Revenue and expense transactions are translated at the approximate exchange rate in effect at the time of the transaction. Foreign exchange gains and losses are included in the statement of operations as foreign exchange gain (loss).

- Definition

The entire disclosure of changes in accounting principles, including adoption of new accounting pronouncements, that describes the new methods, amount and effects on financial statement line items.

+ References

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+ Details

Future Changes in Accounting Policies

3 Months Ended

Mar. 31, 2015

Accounting Changes And Error Corrections [Abstract]

Future changes in accounting policies

4.	Future changes in accounting policies:

In May 2014, the FASB issued amendments to clarify the principles of recognizing revenue and to develop a common revenue standard that would remove inconsistencies in revenue requirements, leading to improved comparability of revenue recognition practices across entities and industries. The amendments stipulate that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Additional disclosure will also be required about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments, and assets recognized from costs incurred to obtain or fulfill a contract. In April 2015, the FASB voted to propose a deferral of the effective date of the new revenue standard by one year. The new guidance would be effective for public entities for fiscal years beginning after December 15, 2017 instead of the originally contemplated effective date of December 15, 2016. Entities are permitted to adopt in accordance with the original effective date if they choose. The Company is currently evaluating the new guidance to determine the impact it will have on the Company’s financial position, results of operations and cash flows.

In August 2014, the FASB issued amendments requiring management to assess an entity’s ability to continue as a going concern. For each reporting period, management will be required to evaluate whether there are conditions or events that raise substantial doubt about a company’s ability to continue as a going concern within one year from the date the financial statements are issued. These amendments will be effective for public entities for the annual period ending after December 15, 2016, and for annual periods and interim periods thereafter. The adoption of these amendments in fiscal 2017 is not expected to have a material impact on the Company’s financial statements.

Net Income (Loss) Per Common Share

3 Months Ended

Mar. 31, 2015

Earnings Per Share [Abstract]

Net Income (Loss) Per Common Share

5.	Net income (loss) per common share:

Basic net income (loss) per common share is computed by dividing the net income (loss) attributable to common shareholders by the weighted average number of common shares outstanding for the period. Diluted net income (loss) per common share is computed by adjusting net income (loss) attributable to common shareholders to reallocate undistributed earnings based on the potential impact of dilutive securities.

Prior to the Company’s IPO, net income (loss) per share was calculated under the two-class method as the Company had outstanding shares that met the definition of participating securities. The two-class method determines net income (loss) per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income available to common shareholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. All of the outstanding redeemable convertible preferred shares converted to common shares upon the consummation of the Company’s IPO.

As the Company reported a net loss attributable to common shareholders for the three months ended March 31, 2015 and no net income was attributable to common shareholders for the three months ended March 31, 2014, all stock options were anti-dilutive and were excluded from the diluted weighted average shares outstanding for both periods.

- Definition

The entire disclosure for earnings per share.

+ References+ Details

Fair Value of Financial Instruments

3 Months Ended

Mar. 31, 2015

Fair Value Disclosures [Abstract]

Fair value of financial instruments

6.	Fair value of financial instruments:

U.S. GAAP establishes a fair value hierarchy for inputs to be used to measure fair value of financial assets and liabilities. This hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three levels: Level 1 (highest priority), Level 2, and Level 3 (lowest priority).

·	Level 1 - Unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the balance sheet date.

Level 2 - Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (i.e., interest rates, yield curves, etc.), and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market corroborated inputs).

·	Level 3 - Inputs are unobservable and reflect the Company’s assumptions as to what market participants would use in pricing the asset or liability. The Company develops these inputs based on the best information available.

The Company’s Level 1 assets include cash and cash equivalents and marketable securities with quoted prices in active markets. The carrying amount of accounts receivables, accounts payable and accrued expenses approximates fair value due to the nature and short-term of those instruments.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References+ Details

Accounts Payable and Accrued Expenses

3 Months Ended

Mar. 31, 2015

Payables And Accruals [Abstract]

Accounts payable and accrued expenses

7.	Accounts payable and accrued expenses:

Accounts payable and accrued expenses consisted of the following:

	March 31,		December 31,
	2015		2014
Trade payables	$	632	$	553
Employee compensation, benefits, and related accruals		384		1,077
Consulting and contracted research		288		774
Professional fees		171		180
Other		55		80
Total	$	1,530	$	2,664

Stock Option Plan

3 Months Ended

Mar. 31, 2015

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock option plan

8.	Stock option plan:

The following table presents stock option activity for the period:

	Three Months Ended March 31,
	2015			2014
Outstanding, beginning of period		1,484,218			1,333,099
Granted		346,964			157,231
Exercised⁽¹⁾		(44,656	)		(772	)
Forfeited and expired		(1,090	)		(44,238	)
Outstanding, end of period		1,785,436			1,445,320
Exercisable, end of period		1,146,383			999,089

(1)	During the three months ended March 31, 2015, 26,910 stock options were exercised for the same number of common shares for cash. In the same period, the Company issued 14,032 common shares for the cashless exercise of 17,746 stock options.

The fair value of each option issued to employees and non-employees is estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions:

	Three Months Ended March 31,
	2015			2014
Average risk-free interest rate		1.71	%		1.97	%
Average expected term (in years)		6.25			6.20
Expected volatility		75	%		74	%
Expected dividend yield		0.00	%		0.00	%
Expected forfeiture rate		0.00	%		0.00	%

The weighted-average fair value of options granted during the three months ended March 31, 2015 was $11.84 (three months ended March 31, 2014 - $6.57) per option.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References+ Details

Collaboration Agreements

3 Months Ended

Mar. 31, 2015

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Collaboration Agreements

9.	Collaboration agreements:

The Company has entered into a number of collaboration agreements with multiple deliverables under which it may have received non-refundable upfront payments. The Company generally recognizes revenue from upfront payments ratably over the term of its estimated period of performance of research under its collaboration agreements in the event that such arrangements represent a single unit of accounting. The collaborations may also include contractual milestone payments, which relate to the achievement of prespecified research, development, regulatory and commercialization events. The milestone events coincide with the progression of product candidates from research and development, to regulatory approval and through to commercialization. The process of successfully discovering a new product candidate, having it selected by the collaborator for development and having it approved and ultimately sold for a profit is highly uncertain. As such, the milestone payments that the Company may earn from its collaborators involve a significant degree of risk to achieve.

The following table is a summary of the revenue recognized from the Company’s collaborations for the three months ended March 31, 2015 and 2014:

	Three Months Ended March 31,
	2015		2014
Teva:
Recognition of upfront payment	$	2,876	$	3,025
Research funding		45		80
Genentech:
Recognition of upfront payment		179		786
Research funding		910		1,110
Total collaboration revenue	$	4,010	$	5,001

Commitments and Contingencies

3 Months Ended

Mar. 31, 2015

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

10.	Commitments and contingencies:

The Company has entered into license and research agreements with third parties that include indemnification provisions that are customary in the industry. These indemnification provisions generally require the Company to compensate the other party for certain damages and costs incurred as a result of third party claims or damages arising from these transactions.

The maximum amount of potential future indemnification is unlimited; however, the Company currently holds commercial and product liability insurance. This insurance limits the Company’s exposure and may enable it to recover a portion of any future amounts paid. Historically, the Company has not made any indemnification payments under such agreements and the Company believes that the fair value of these indemnification obligations is minimal. Accordingly, the Company has not recognized any liabilities relating to these obligations for any period presented.

- Definition

The entire disclosure for commitments and contingencies.

+ References+ Details

Accounts Payable and Accrued Expenses (Tables)

3 Months Ended

Mar. 31, 2015

Payables And Accruals [Abstract]

Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses consisted of the following:

	March 31,		December 31,
	2015		2014
Trade payables	$	632	$	553
Employee compensation, benefits, and related accruals		384		1,077
Consulting and contracted research		288		774
Professional fees		171		180
Other		55		80
Total	$	1,530	$	2,664

Stock Option Plan (Tables)

3 Months Ended

Mar. 31, 2015

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Share-based Compensation, Stock Options, Activity

The following table presents stock option activity for the period:

	Three Months Ended March 31,
	2015			2014
Outstanding, beginning of period		1,484,218			1,333,099
Granted		346,964			157,231
Exercised⁽¹⁾		(44,656	)		(772	)
Forfeited and expired		(1,090	)		(44,238	)
Outstanding, end of period		1,785,436			1,445,320
Exercisable, end of period		1,146,383			999,089

(1)	During the three months ended March 31, 2015, 26,910 stock options were exercised for the same number of common shares for cash. In the same period, the Company issued 14,032 common shares for the cashless exercise of 17,746 stock options.

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The fair value of each option issued to employees and non-employees is estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions:

	Three Months Ended March 31,
	2015			2014
Average risk-free interest rate		1.71	%		1.97	%
Average expected term (in years)		6.25			6.20
Expected volatility		75	%		74	%
Expected dividend yield		0.00	%		0.00	%
Expected forfeiture rate		0.00	%		0.00	%

Collaboration Agreements (Tables)

3 Months Ended

Mar. 31, 2015

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Revenue Recognized From Collaborations

The following table is a summary of the revenue recognized from the Company’s collaborations for the three months ended March 31, 2015 and 2014:

	Three Months Ended March 31,
	2015		2014
Teva:
Recognition of upfront payment	$	2,876	$	3,025
Research funding		45		80
Genentech:
Recognition of upfront payment		179		786
Research funding		910		1,110
Total collaboration revenue	$	4,010	$	5,001

Nature of the Business (Details) (USD $)	3 Months Ended		0 Months Ended		12 Months Ended		0 Months Ended
Nature of the Business (Details) (USD $)	Mar. 31, 2015	Nov. 10, 2014	Nov. 10, 2014 Converted from Convertible Preferred Shares [Member]	Nov. 10, 2014 Converted from Subscription Rights [Member]	Dec. 31, 2014 Common Stock [Member]	Nov. 10, 2014 Common Stock [Member]	Nov. 10, 2014 Common Stock [Member] IPO [Member]	Nov. 10, 2014 Common Stock [Member] Private Placement [Member] Genentech Affiliate [Member]	Oct. 01, 2014 Common Stock [Member] Reverse Stock Split [Member]	Oct. 01, 2014 Series A Preferred Stock [Member] Preferred Stock [Member] Reverse Stock Split [Member]	Oct. 01, 2014 Series B Preferred Stock [Member] Preferred Stock [Member] Reverse Stock Split [Member]	Oct. 01, 2014 Series E Preferred Stock [Member] Preferred Stock [Member] Reverse Stock Split [Member]	Mar. 31, 2015 Series C Preferred Stock [Member]	Mar. 31, 2015 Series D Preferred Stock
Note 1 - Nature of the Business (Details) [Line Items]
Stockholders' Equity Note, Stock Split, Conversion Ratio									4.86	4.86	4.86	4.86
Stockholders' Equity Note, Reverse Stock Split	On October 1, 2014, the Company effected a 1 for 4.86 reverse share split of its common and Series A, B and E redeemable convertible preferred shares. At the time of the consolidation, there were no outstanding Series C and D preferred shares and therefore such series were not included in the consolidation. Accordingly, (i) every 4.86 common shares were combined into one common share, (ii) every 4.86 redeemable Series A, B and E convertible preferred shares were combined into one redeemable convertible preferred share, (iii) the number of common shares into which each outstanding subscription right was exchangeable into common shares were proportionately decreased on a 1 for 4.86 basis, (iv) the number of common shares into which each outstanding option to purchase common shares was exercisable were proportionately decreased on a 1 for 4.86 basis, and (v) the exercise price for each such outstanding option to purchase common shares was proportionately increased on a 1 for 4.86 basis. All of the share numbers, share prices, and exercise prices prior to October 1, 2014 have been adjusted, on a retroactive basis, to reflect this 1 for 4.86 reverse share split.
Preferred Stock, Shares Outstanding		0											0	0
Issuance of common shares, net of issuance costs (in Shares)					5,095,000		4,600,000	495,000
Share Price (in Dollars per share)							$ 9.00	$ 9.00
Subscribed common stock issued			7,725,924	10,201
Subscription rights converted into common shares						10,201
Preferred Stock, Subscription Rights Outstanding		0

Accounts Payable and Accrued Expenses - Accounts Payable and Accrued Expenses (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Payables And Accruals [Abstract]
Trade payables	$ 632	$ 553
Employee compensation, benefits, and related accruals	384	1,077
Consulting and contracted research	288	774
Professional fees	171	180
Other	55	80
Total	$ 1,530	$ 2,664

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable for professional fees, such as for legal and accounting services received. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References+ Details

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable arising from transactions not otherwise specified in the taxonomy. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References+ Details

Stock Option Plan - Stock Option Activity (Details)

3 Months Ended

Mar. 31, 2015

Mar. 31, 2014

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Outstanding, beginning of period

1,484,218

1,333,099

Granted

346,964

157,231

Exercised

(44,656)

^[1]

(772)

^[1]

Forfeited and expired

(1,090)

(44,238)

Outstanding, end of period

1,785,436

1,445,320

Exercisable, end of period

1,146,383

999,089

[1]	During the three months ended March 31, 2015, 26,910 stock options were exercised for the same number of common shares for cash. In the same period, the Company issued 14,032 common shares for the cashless exercise of 17,746 stock options.

- Definition

Number of share options (or share units) exercised during the current period.

+ References+ Details

Stock Option Plan - Stock Option Activity (Parenthetical) (Details)	3 Months Ended
	Mar. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock options exercised for number of common shares for cash	26,910
Common stock issued for cashless exercise	14,032
Cashless exercise of stock options	17,746

Stock Option Plan - Fair Value Assumptions for Stock Options (Details)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Fair Value Assumptions For Stock Options [Abstract]
Average risk-free interest rate	1.71%	1.97%
Average expected term (in years)	6 years 3 months	6 years 2 months 12 days
Expected volatility	75.00%	74.00%
Expected dividend yield	0.00%	0.00%
Expected forfeiture rate	0.00%	0.00%

Collaboration Agreements - Revenue Recognized from Collaborations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Deferred Revenue Arrangement [Line Items]
Collaboration revenue	$ 4,010	$ 5,001
Teva [Member] \| Recognition of Upfront Payment [Member] \| Collaborative Arrangement [Member]
Deferred Revenue Arrangement [Line Items]
Collaboration revenue	2,876	3,025
Teva [Member] \| Research Funding [Member] \| Collaborative Arrangement [Member]
Deferred Revenue Arrangement [Line Items]
Collaboration revenue	45	80
Genentech [Member] \| Recognition of Upfront Payment [Member] \| Collaborative Arrangement [Member]
Deferred Revenue Arrangement [Line Items]
Collaboration revenue	179	786
Genentech [Member] \| Research Funding [Member] \| Collaborative Arrangement [Member]
Deferred Revenue Arrangement [Line Items]
Collaboration revenue	$ 910	$ 1,110

Stock Option Plan (Details) (USD $)	3 Months Ended
Stock Option Plan (Details) (USD $)	Mar. 31, 2015	Mar. 31, 2014
Fair Value Assumptions For Stock Options [Abstract]
Weighted Average Grant Date Fair Value, Granted	$ 11.84	$ 6.57