Microbot Medical (MBOT) 10-Q 5 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 30, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	STEM
Entity Registrant Name	STEMCELLS INC
Entity Central Index Key	883975
Current Fiscal Year End Date	-19
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		105,097,782

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (Unaudited) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$14,145,901	$24,987,603
Trade receivables	17,169	159,466
Other receivables	166,767	256,166
Prepaid assets	970,573	1,017,726
Deferred financing costs, current	15,144	22,082
Other assets, current	63,763	64,928
Total current assets	15,379,317	26,507,971
Property, plant and equipment, net	5,159,997	5,186,958
Deferred financing costs, non-current		1,224
Other assets, non-current	373,717	373,717
Intangible assets, net	336,027	356,889
Total assets	21,249,058	32,426,759
Current liabilities:
Accounts payable	1,677,534	1,818,831
Accrued expenses and other current liabilities	3,301,153	4,869,710
Deferred revenue, current	16,826	16,826
Capital lease obligation, current	18,527	20,191
Deferred rent, current	98,791	85,925
Loan payable net of discount, current	4,097,837	4,686,388
Total current liabilities	9,210,668	11,497,871
Capital lease obligations, non-current	5,322	9,230
Loan payable net of discount, non-current	9,274,959	10,334,029
Fair value of warrant liability	2,031,881	1,684,551
Other long-term liabilities	1,319,829	1,250,007
Deferred rent, non-current	1,710,679	1,734,214
Deferred revenue, non-current	41,878	46,084
Total liabilities	23,595,216	26,555,986
Commitments and contingencies (Note 7)
Stockholders' equity:
Common stock, $0.01 par value; 225,000,000 shares authorized; issued and outstanding 69,311,545 at March 31, 2015 and 68,729,774 at December 31, 2014	693,116	687,298
Additional paid-in capital	426,550,087	425,389,693
Accumulated deficit	-429,622,309	-420,271,608
Accumulated other comprehensive income	32,948	65,390
Total stockholders' equity	-2,346,158	5,870,773
Total liabilities and stockholders' equity	$21,249,058	$32,426,759

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Common stock, par value	$0.01	$0.01
Common stock, shares authorized	225,000,000	225,000,000
Common stock, shares issued	69,311,545	68,729,774
Common stock, shares outstanding	69,311,545	68,729,774

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (Unaudited) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Revenue:
Revenue from licensing agreements	$20,997	$23,584
Operating expenses:
Research and development	6,292,191	4,629,673
General and administrative	2,689,196	2,236,014
Total operating expenses	8,981,387	6,865,687
Loss from operations	-8,960,390	-6,842,103
Other income (expense):
Change in fair value of warrant liability	-347,330	-326,624
Interest income	1,394	2,185
Interest expense	-185,356	-380,488
Other income (expense), net	140,981	-15,498
Total other expense, net	-390,311	-720,425
Net loss from continuing operations	-9,350,701	-7,562,528
Discontinued operations:
Loss from discontinued operations		-57,728
Net loss	($9,350,701)	($7,620,256)
Basic and diluted net loss per share:
Basic and diluted net loss per share from continuing operations	($0.14)	($0.14)
Basic and diluted net loss per share from discontinued operations	$0	$0
Basic and diluted net loss per share	($0.14)	($0.14)
Weighted average number of common shares outstanding, basic and diluted	69,219,964	55,343,877

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net and comprehensive loss from continuing operations	($9,350,701)	($7,562,528)
Discontinued operations:
Net loss from discontinued operations		-57,728
Foreign currency translation adjustments	-32,442	13,460
Comprehensive loss from discontinued operations	-32,442	-44,268
Comprehensive loss	($9,383,143)	($7,606,796)

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net loss	($9,350,701)	($7,620,256)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	269,604	335,855
Stock-based compensation	1,308,894	521,106
Amortization of debt discount and issuance costs	42,206	72,836
Gain on disposal of fixed assets	-148,713
Change in fair value of warrant liability	347,330	326,624
Changes in operating assets and liabilities:
Trade receivables	138,071	8,662
Accrued interest and other receivables	85,317	387,686
Prepaid and other current assets	46,312	102,895
Accounts payable and accrued expenses	-1,630,659	-637,190
Deferred revenue	-4,206	-10,340
Deferred rent	-10,670	4,576
Net cash used in operating activities	-8,907,215	-6,507,546
Cash flows from investing activities:
Purchases of property, plant and equipment	-221,782	-230,689
Proceeds from sale of property, plant and equipment	148,713
Net cash used in investing activities	-73,069	-230,689
Cash flows from financing activities:
Proceeds from loan payable		3,820,264
Payments related to net share issuance of stock based awards	-142,683	-201,462
Repayment of capital lease obligations	-5,573	-5,186
Repayment of loan payable	-1,681,664	-998,089
Net cash provided by (used in) financing activities	-1,829,920	2,615,527
Decrease in cash and cash equivalents	-10,810,204	-4,122,708
Effects of foreign exchange rate changes on cash	-31,498	909
Cash and cash equivalents, beginning of period	24,987,603	30,585,424
Cash and cash equivalents, end of period	14,145,901	26,463,625
Supplemental disclosure of cash flow information:
Interest paid	$78,508	$141,249

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 1. Summary of Significant Accounting Policies
	Nature of Business.
	StemCells, Inc., a Delaware corporation, is a biopharmaceutical company that operates in one segment, the research, development, and commercialization of stem cell therapeutics and related technologies.
	The accompanying financial data as of March 31, 2015 and for the three months ended March 31, 2015 and 2014 have been prepared by us, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States (U.S. GAAP) have been condensed or omitted pursuant to these rules and regulations. The December 31, 2014 condensed consolidated balance sheet was derived from audited financial statements, but does not include all disclosures required by U.S. GAAP. However, we believe that the disclosures are adequate to make the information presented not misleading. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and the notes thereto included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2014.
	We have incurred significant operating losses since inception. We expect to incur additional operating losses over the foreseeable future. We have very limited liquidity and capital resources and must obtain significant additional capital and other resources in order to provide funding for our product development efforts, the acquisition of technologies, businesses and intellectual property rights, preclinical and clinical testing of our products, pursuit of regulatory approvals, acquisition of capital equipment, laboratory and office facilities, establishment of production capabilities, general and administrative expenses and other working capital requirements. We rely on our cash reserves, proceeds from equity and debt offerings, credit facilities, proceeds from the transfer or sale of intellectual property rights, equipment, facilities or investments, government grants and funding from collaborative arrangements, to fund our operations. If we exhaust our cash reserves and are unable to obtain adequate financing, we may be unable to meet our operating obligations and we may be required to initiate bankruptcy proceedings. The financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that may result from the outcome of this uncertainty.
	Principles of Consolidation
	The condensed consolidated financial statements include the accounts of StemCells, Inc., and our wholly-owned subsidiaries, including StemCells California, Inc., Stem Cell Sciences Holdings Ltd, and Stem Cell Sciences (UK) Ltd (SCS). All significant intercompany accounts and transactions have been eliminated.
	Reclassifications
	Certain reclassifications have been made to the prior year financial statements in order to conform to the current year’s presentation.
	Use of Estimates
	The preparation of financial statements in conformity with U.S. GAAP requires management to make judgments, assumptions and estimates that affect the amounts reported in our condensed consolidated financial statements and accompanying notes. Actual results could differ materially from these estimates.
	Significant estimates include the following:
	•	the grant date fair value of stock-based awards recognized as compensation expense (see Note 5, “Stock-Based Compensation”);
	•	the fair value of warrants recorded as a liability (see Note 8, “Warrant Liability”).
	Discontinued Operations
	The results of operations of a business that either has been disposed of or is classified as held-for-sale are reported in discontinued operations if the operations and cash flows of the component have been or will be eliminated from our ongoing operations as a result of the disposal transaction and we will not have any significant continuing involvement in the operations of the component after the disposal transaction. We present the operations of a business that meet this criteria as a discontinued operation, and retrospectively reclassify operating results for all prior periods presented. In the fourth quarter of 2014, as part of our strategy to focus on our clinical operations, we sold our SC Proven reagent and cell culture business and wound-down our business operations at our Stem Cell Sciences Subsidiary in Cambridge, UK (SCS). The results of operations for this component have been classified as discontinued operations for all periods in our Consolidated Statement of Operations.
	Financial Instruments
	Cash and Cash Equivalents
	Cash equivalents are money market accounts, money market funds and investments with maturities of 90 days or less from the date of purchase.
	Receivables
	Our receivables generally consist of interest income on our financial instruments and royalties due from licensing agreements.
	Warrant Liability
	We account for our warrants in accordance with U.S. GAAP which defines how freestanding contracts that are indexed to and potentially settled in a company’s own stock should be measured and classified. Authoritative accounting guidance prescribes that only warrants issued by us under contracts that cannot be net-cash settled, and are both indexed to and settled in our common stock, can be classified as equity. As part our November 2009 financing, we issued warrants with five year terms to purchase 400,000 shares of our common stock at $15.00 per share. As part of our December 2011 financing, we issued Series A Warrants with a five year term to purchase 8,000,000 shares at $1.40 per share and Series B Warrants with a ninety trading day term to purchase 8,000,000 units at $1.25 per unit. Each unit underlying the Series B Warrants consisted of one share of our common stock and one Series A Warrant. In the first and second quarter of 2012, an aggregate of 2,700,000 Series B Warrants were exercised. For the exercise of these warrants, we issued 2,700,000 shares of our common stock and 2,700,000 Series A Warrants. The remaining 5,300,000 Series B Warrants expired unexercised by their terms on May 2, 2012. As terms of the warrants issued in 2009, as well as the Series A and Series B Warrants, do not meet the specific conditions for equity classification, we are required to classify the fair value of these warrants as a liability, with subsequent changes in fair value to be recorded as income (loss) due to change in fair value of warrant liability. The fair value of the warrants issued in the 2009 financing is determined using the Black-Scholes-Merton (Black-Scholes) option pricing model and the fair value of the Series A and Series B Warrants is determined using a Monte Carlo simulation model (see Note 8, “Warrant Liability”). The fair value is affected by changes in inputs to these models including our stock price, expected stock price volatility, the contractual term, and the risk-free interest rate. The use of a Monte Carlo simulation model requires input of additional assumptions including the progress of our R&D programs and its affect on potential future financings. We will continue to classify the fair value of the warrants as a liability until the warrants are exercised, expire or are amended in a way that would no longer require these warrants to be classified as a liability. The estimated fair value of our warrant liability at March 31, 2015, was approximately $2,032,000.
	Goodwill and Other Intangible Assets
	Goodwill and intangible assets deemed to have indefinite lives are not amortized but are subject to annual impairment tests. If the assumptions and estimates used to allocate the purchase price are not correct, or if business conditions change, purchase price adjustments or future asset impairment charges could be required. We test goodwill for impairment on an annual basis or more frequently if we believe indicators of impairment exist. Impairment evaluations involve management estimates of asset useful lives and future cash flows. Significant management judgment is required in the forecasts of future operating results that are used in the evaluations, and it is possible, even likely, that the plans and estimates used may be incorrect. On April 1, 2009, we acquired the operations of SCS for an aggregate purchase price of approximately $5,135,000. Approximately 42% of the purchase price was allocated to Goodwill. The acquired operations included proprietary cell technologies relating to embryonic stem cells, induced pluripotent stem (iPS) cells, and tissue-derived (adult) stem cells; expertise and infrastructure for providing cell-based assays for drug discovery; a cell culture products business; and an intellectual property portfolio with claims relevant to cell processing, reprogramming and manipulation, as well as to gene targeting and insertion. In the fourth quarter of 2014, as part of our strategy to focus on our clinical operations, we sold our SC Proven reagent and cell culture business and wound-down our business operations at our SCS Subsidiary in Cambridge, UK. We also determined that we could not predict the future cash flows if any from the intellectual property portfolio acquired. Based on these factors, we determined that the Goodwill related to the acquisition was impaired and wrote off its carrying value of approximately $1,910,000 in the fourth quarter of 2014.
	Prior to fiscal year 2001, we capitalized certain patent costs, which are being amortized over the estimated life of the patent and would be expensed at the time such patents are deemed to have no continuing value. Since 2001, all patent costs are expensed as incurred. License costs are capitalized and amortized over the estimated life of the related license agreement.
	Revenue Recognition
	We currently recognize revenue resulting from the licensing and use of our technology and intellectual property. Licensing agreements may contain multiple elements, such as upfront fees, payments related to the achievement of particular milestones and royalties. Revenue from upfront fees for licensing agreements that contain multiple elements are generally deferred and recognized on a straight-line basis over the term of the agreement. Fees associated with substantive at risk performance-based milestones are recognized as revenue upon completion of the scientific or regulatory event specified in the agreement, and royalties received are recognized as earned. Revenue from licensing agreements is recognized net of a fixed percentage due to licensors as royalties.
	Stock-Based Compensation
	Compensation expense for stock-based payment awards to employees is based on their grant date fair value as calculated and amortized over their vesting period. See Note 5, “Stock-Based Compensation” for further information.
	We use the Black-Scholes model to calculate the fair value of stock-based awards.
	Per Share Data
	Basic net income or loss per share is computed by dividing net income or loss by the weighted average number of shares of common stock outstanding during the period. Diluted net income or loss per share is computed based on the weighted average number of shares of common stock and other dilutive securities. To the extent these securities are anti-dilutive, they are excluded from the calculation of diluted earnings per share.
	The following is a reconciliation of the numerators and denominators of the basic and diluted net loss per share computations:
		Three months ended March 31,
		2015			2014
	Net loss from continuing operations	$	(9,350,701	)	$	(7,562,528	)
	Net loss from discontinued operations		—			(57,728	)
	Net loss	$	(9,350,701	)	$	(7,620,256	)
	Weighted average shares outstanding used to compute basic and diluted net income or loss per share		69,219,964			55,343,877
	per share
	Basic and diluted net loss per share from continuing operations	$	(0.14	)	$	(0.14	)
	Basic and diluted net loss per share from discontinued operations		—			—
	Basic and diluted net loss per share	$	(0.14	)	$	(0.14	)
	The following outstanding potentially dilutive securities were excluded from the computation of diluted net income or loss per share because the effect would have been anti-dilutive as of March 31:
		2015			2014
	Options		276,229			381,851
	Restricted stock units		9,984,519			3,144,940
	Warrants		23,478,181			16,267,659
	Total		33,738,929			19,794,450
	Comprehensive Income (Loss)
	Comprehensive income (loss) is comprised of net income or loss and other comprehensive income or loss (OCL). OCL includes certain changes in stockholders’ equity that are excluded from net income or loss. Specifically, when applicable, we include in OCL changes in unrealized gains and losses on foreign currency translations. Accumulated other comprehensive income was $32,948 as of March 31, 2015, and accumulated other comprehensive income was $65,390, as of December 31, 2014.

Financial_Instruments

Financial Instruments	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Financial Instruments	Note 2. Financial Instruments
	The following table summarizes the fair value of our cash and cash equivalents held in our current investment portfolio:
		Amortized		Gross		Gross		Fair Value
		Cost		Unrealized		Unrealized
				Gains		(Losses)
	March 31, 2015
	Cash	$	2,655,834	$	—	$	—	$	2,655,834
	Cash equivalents		11,490,067		—		—		11,490,067
	Total cash and cash equivalents	$	14,145,901	$	—	$	—	$	14,145,901
		Amortized		Gross		Gross		Fair Value
		Cost		Unrealized		Unrealized
				Gains		(Losses)
	December 31, 2014
	Cash	$	1,398,928	$	—	$	—	$	1,398,928
	Cash equivalents		23,588,675		—		—		23,588,675
	Total cash and cash equivalents	$	24,987,603	$	—	$	—	$	24,987,603
	At March 31, 2015, our investments in money market accounts are through a money market fund that invests in high quality, short-term money market instruments which are classified as cash equivalents in the accompanying Condensed Consolidated Balance Sheet due to their short maturities. The investment seeks to provide the highest possible level of current income while still maintaining liquidity and preserving capital. From time to time, we carry cash balances in excess of federally insured limits.

Fair_Value_Measurement

Fair Value Measurement	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurement	Note 3. Fair Value Measurement
	Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. As a basis for considering such assumptions, we are required to apply a three-tier value hierarchy, which prioritizes the inputs used in the valuation methodologies in measuring fair value. The three levels of the fair value hierarchy are:
	Level 1 — Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets.
	Level 2 — Directly or indirectly observable inputs other than in Level 1, that include quoted prices for similar assets or liabilities in active markets or quoted prices for identical or similar assets or liabilities in markets that are not active.
	Level 3 — Unobservable inputs which are supported by little or no market activity that reflects the reporting entity’s own assumptions about the assumptions that market participants would use in pricing the asset or liability.
	The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Assets measured at fair value are classified below based on the three fair value hierarchy tiers described above.
	Our cash equivalents are classified as Level 1 because they are valued primarily using quoted market prices.
	Our liability for warrants issued in our 2009 financing, are classified as Level 2 as they are valued using alternative pricing sources and models utilizing market observable inputs. The fair value of the liability related to these warrants were not significant.
	We estimated the fair value of our loan payable using the net present value of the payments discounted at an effective interest rate. We believe the estimates used to measure the fair value of our loan payable constitute Level 3 inputs.
	Our liability for warrants issued in our 2011 financing is classified as Level 3 as the liability is valued using a Monte Carlo simulation model. Some of the significant inputs used to calculate the fair value of warrant liability include our stock price on the valuation date, expected volatility of our common stock as traded on NASDAQ, and risk-free interest rates that are derived from the yield on U.S. Treasury debt securities, all of which are observable from active markets. However, the use of a Monte Carlo simulation model requires the input of additional subjective assumptions including management’s assumptions regarding the likelihood of a re-pricing of these warrants pursuant to anti-dilution provisions and the progress of our R&D programs and its affect on potential future financings.
	The following table presents financial assets and liabilities measured at fair value as of March 31, 2015:
		Fair Value Measurement
		at Report Date Using
		Quoted Prices			Significant		Unobservable		As of
		in Active Markets			Other		Inputs		March 31,
		for			Observable		(Level 3)		2015
		Identical Assets			Inputs
		(Level 1)			(Level 2)
	Financial assets:
	Cash equivalents:
	Money market funds	$	321,444		$	—	$	—	$	321,444
	U.S. Treasury debt obligations		11,168,623			—		—		11,168,623
	Total financial assets	$	11,490,067		$	—	$	—	$	11,490,067
	Financial liabilities:
	Loan payable net of discounts		—			—		13,372,796		13,372,796
	Warrant liabilities		—			—		2,031,881		2,031,881
	Total financial liabilities	$	—		$	—	$	15,404,677	$	15,404,677
	Level 3 Reconciliation
	The following table presents a roll forward for liabilities measured at fair value using significant unobservable inputs (Level 3) for 2015:
		Warrant
		liabilities
	Balance at December 31, 2014	$	1,684,551
	Add change in fair value of warrants		347,330
	Balance at March 31, 2015	$	2,031,881
		Loan payable net of discounts
	Balance at December 31, 2014	$	15,020,417
	Add amortization of discount		34,043
	Less repayments of principal		(1,681,664	)
	Balance at March 31, 2015	$	13,372,796
	Current portion		4,097,837
	Non-current portion		9,274,959
	Balance at March 31, 2015	$	13,372,796

Intangible_Assets

Intangible Assets	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	Note 4. Intangible Assets
	The components of our intangible assets at March 31, 2015 are summarized below:
	Intangible Asset Class	Cost		Accumulated			Net		Weighted
				Amortization			Carrying		Average
							Amount		Amortization
									Period
	Patents	$	1,243,612	$	(907,585	)	$	336,027		17 years
	Amortization expense was approximately $21,000 in the first quarter of 2015 and expected amortization expense for the year ended December 31, 2015 is approximately $83,000
	The expected future annual amortization expense for each of the next five years based on current balances of our intangible assets is approximately as follows:
	For the year ending December 31:
	2016	$	75,496
	2017	$	54,923
	2018	$	27,978
	2019	$	27,978
	2020	$	26,594

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Note 5. Stock-Based Compensation
	We currently grant stock-based compensation under two equity incentive plans (2006 and 2013 Equity Incentive Plans) approved by the Company’s stockholders and one plan adopted in 2012 pursuant to NASDAQ Listing Rule 5635(c)(4) concerning inducement grants for new employees (our “2012 Commencement Incentive Plan”). As of March 31, 2015, we had 7,856,374 shares available to grant under the above mentioned plans. At our annual stockholders meeting held on June 12, 2007, our stockholders approved an amendment to our 2006 Equity Incentive Plan to provide for an annual increase in the number of shares of common stock available for issuance under the plan each January 1 (beginning January 1, 2008) equal to 4% of the outstanding common shares as of that date. The amendment further provided an aggregate limit of 3,000,000 shares issuable pursuant to incentive stock option awards under the plan. At our annual stockholders meeting held on December 20, 2013, our stockholders approved our 2013 Equity Incentive Plan to grant stock-based compensation of up to an initial 6,000,000 shares, plus an increase of 4% per year of the outstanding number of shares of our common stock beginning in January 1, 2015. Under the three stockholder-approved plans we may grant incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock, restricted stock units, 401(k) Plan employer match in form of shares and performance-based shares to our employees, directors and consultants, at prices determined by our Board of Directors. Incentive stock options may only be granted to employees under these plans with a grant price not less than the fair market value on the date of grant. Under our 2012 Commencement Inducement Plan, we may only award options, restricted stock units and other equity awards to newly hired employees and newly engaged directors, in each case as allowed by NASDAQ listing requirements.
	Generally, stock options and restricted stock units granted to employees have a maximum term of ten years, and vest over a four year period from the date of grant; 25% vest at the end of one year, and 75% vest monthly over the remaining three-year service period. We may grant options and restricted stock units with different vesting terms from time to time. Upon employee termination of service, any unexercised vested option will be forfeited three months following termination or the expiration of the option, whichever is earlier.
	Our stock-based compensation expense for the three months ended March 31 was as follows:
			Three months ended
			March 31,
			2015			2014
	Research and development expense		$	583,669		$	186,293
	General and administrative expense			725,225			334,813
	Total stock-based compensation		$	1,308,894		$	521,106
	Effect on basic and diluted net loss per share		$	(0.02	)	$	(0.01	)
	As of March 31, 2015, we had approximately $9,884,000 of total unrecognized compensation expense related to unvested awards of stock options and restricted stock units granted under our various equity incentive plans that we expect to recognize over a weighted-average vesting period of 2.4 years.
	Stock Options
	A summary of our stock option activity for the three months ended March 31, 2015 is as follows:
			Number of options			Weighted-average
						exercise price ($) per share
	Outstanding options at December 31, 2014			302,729			18.18
	Granted			—			—
	Exercised			—			—
	Cancelled			(26,500	)		13.18
	Outstanding options at March 31, 2015			276,229			18.66
	All options outstanding as of March 31, 2015 are fully vested.
	Restricted Stock Units
	We have granted restricted stock units (RSUs) to certain employees and members of the Board of Directors which entitle the holders to receive shares of our common stock upon vesting of the RSUs. The fair value of restricted stock units granted is based upon the market price of the underlying common stock as if it were vested and issued on the date of grant.
	A summary of changes in our restricted stock units for the three months ended March 31, 2015 is as follows:
			Number of RSUs			Weighted Average
						Grant Date
						Fair Value ($)
	Outstanding at December 31, 2014			3,374,940			1.55
	Granted(1)			7,290,768			1.11
	Vested and exercised			(634,090	)		1.21
	Cancelled			(47,100	)		1.51
	Outstanding at March 31, 2015			9,984,518			1.25
	-1	349,518 of these restricted stock units vest and convert into shares of our common stock after one year from the date of grant. 2,586,750 of these restricted stock units will vest and convert into shares of our common stock over a three year period from the date of grant; one-third of the award will vest on each grant date anniversary following the grant. 4,354,500 of these restricted stock units are performance based and vest on achievement of predefined milestones.
	Stock Appreciation Rights
	In July 2006, we granted cash-settled Stock Appreciation Rights (SARs) to certain employees that give the holder the right, upon exercise, to the difference between the price per share of our common stock at the time of exercise and the exercise price of the SARs.
	The SARs have a maximum term of ten years with an exercise price of $20.00, which is equal to the market price of our common stock at the date of grant. The SARs vest 25% on the first anniversary of the grant date and 75% vest monthly over the remaining three-year service period. At March 31, 2015 and 2014, there were 110,593 SARs outstanding. All of the outstanding SARs as of March 31, 2015 are fully vested. There were no SARs granted, exercised or forfeited during the three months ended March 31, 2015. Compensation expense is based on the fair value of SARs which is calculated using the Black-Scholes option pricing model.
	The stock-based compensation expense and liability are re-measured at each reporting date through the earlier of date of settlement or forfeiture of the SARs. For the three months ended March 31, 2015 and 2014, the re-measured liability and expense for the respective periods related to the SARs were not significant.
	The compensation expense related to the SARs recognized for the three months ended March 31, 2015 may not be representative of compensation expense for future periods and its resulting effect on net loss and net loss per share attributable to common stockholders, due to changes in the fair value calculation which is dependent on the stock price, volatility, interest and forfeiture rates, additional grants and subsequent periods of vesting. We will continue to recognize compensation cost each period, which will be the change in fair value from the previous period through the earlier date of settlement or forfeiture of the SARs.

Loan_Payable

Loan Payable	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Loan Payable	Note 6. Loan Payable
	Loan Agreement with Silicon Valley Bank
	In April 2013, we entered into a Loan Agreement with Silicon Valley Bank (SVB) and received loan proceeds of $9,900,000, net of a $100,000 cash discount. The loan proceeds will be used for research and development and general corporate purposes. The loan has a three-year term and bears interest at an annual rate of 6%. The loan obligations are secured by a first priority security interest on substantially all of our assets excluding intellectual property. For the first six months, payments will be interest only followed by repayment of principal and interest over a period of 30 months. There is also a final $1,000,000 fee payable at the end of the term which is being expensed over the term of the loan using the effective interest method. In conjunction with the Loan Agreement, we issued to SVB a ten year warrant to acquire 293,531 shares of common stock at an exercise price of $1.7034 per share. The warrant is immediately exercisable and expires in April 2023. We estimated the fair value of the warrant to be approximately $388,000 using the Black-Scholes option pricing model with the following assumptions:
	Expected life (years)		10
	Risk-free interest rate		1.9	%
	Expected volatility		88.1	%
	Expected dividend yield		0	%
	We applied the relative fair value method to allocate the $9,900,000 net proceeds between the loan and warrant. The approximately $388,000 fair value allocated to the warrant was recorded as an increase to additional paid-in capital and as a discount to loan payable. Approximately $9,512,000 was assigned to the loan and was recorded as the initial carrying amount of the loan payable, net of discount. The approximately $388,000 fair value of the warrant and the $100,000 cash discount are both being amortized as additional interest expense over the term of the loan using the effective interest rate method.
	We also incurred loan issuance costs of approximately $117,000, which are recorded as deferred financing costs on the accompanying consolidated balance sheet and are being amortized to interest expense over the term of the Loan Agreement using the effective interest rate method.
	The effective interest rate used to amortize the deferred financing costs and the discount (including the fair value of the warrant and the cash discount), and for the accretion of the final payment, is 9.0%.
	Loan Agreement with California Institute for Regenerative Medicine
	In April 2013, we entered into an agreement with the California Institute of Regenerative Medicine (CIRM) under which CIRM would have provided up to approximately $19.3 million as a forgivable loan, in accordance with mutually agreed upon terms and conditions and CIRM regulations. The CIRM loan helped fund preclinical development of our HuCNS-SC cells for Alzheimer’s disease. Between July 2013 and August 2014, we received in aggregate, approximately $9.6 million as disbursements of the loan provided under the CIRM Loan Agreement. However, in December 2014, as findings under this pre-clinical study in Alzheimer’s disease did not meet certain pre-determined criteria for continued funding of this program by CIRM, the parties terminated the loan agreement and we wound down this pre-clinical study which had been funded in part by the CIRM loan agreement. In February 2015, we repaid CIRM approximately $679,000 of the aggregate loan proceeds received. Under the terms of the CIRM loan agreement, principal amount of approximately $8,917,000 and accrued interest of approximately $243,000 were forgiven. However, authoritative accounting guidance requires certain conditions (which includes a legal release from the creditor) to be met before a liability can be extinguished and derecognized.
	The following table is a summary of the changes in the carrying value of our loans payable for the three months ended March 31, 2015:
		Silicon Valley			CIRM Loan			Total
		Bank Loan
	Carrying value of loan payable at 12/31/2014 (current and non-current)	$	5,424,610		$	9,595,807		$	15,020,417
	Repayment of principal		(1,002,498	)		(679,166	)		(1,681,664	)
	Accretion of discount		34,043			—			34,043
	Carrying value of loan payable at 3/31/2015 (current and non-current)	$	4,456,155		$	8,916,641		$	13,372,796
	Carrying value of loan payable, current portion	$	4,097,837		$	—		$	4,097,837
	Carrying value of loan payable, non-current portion		358,318			8,916,641			9,274,959
	Total loan payable at 03/31/2015	$	4,456,155		$	8,916,641		$	13,372,796

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 7. Commitments and Contingencies
	Bonds Payable
	We entered into direct financing transactions with the State of Rhode Island and received proceeds from the issuance of industrial revenue bonds totaling $5,000,000 to finance the construction of a 21,000 square-foot pilot manufacturing facility and a 3,000 square-foot cell processing facility in Lincoln, Rhode Island. The related lease agreements are structured such that lease payments fully fund all semiannual interest payments and annual principal payments through maturity in August 2014. In August 2014, we made the final principal and interest payment thereby extinguishing the debt, In March 2015, we sold the vacant 21,000 square-foot pilot manufacturing facility and the vacant 3,000 square-foot cell processing facility in Lincoln, Rhode Island to an unrelated third party net of expenses for approximately $149,000.
	Operating leases
	We lease various real properties under operating leases that generally require us to pay taxes, insurance, maintenance, and minimum lease payments. Some of our leases have options to renew.
	Operating Leases — California
	In December 2010, we entered into a commercial lease agreement with BMR-Gateway Boulevard LLC (BMR), as landlord, for office and research space at BMR’s Pacific Research Center in Newark, California. The initial term of the lease is approximately eleven and one-half years and includes escalating rent payments which we recognize as lease operating expense on a straight-line basis. We will pay approximately $17,869,000 in aggregate as rent over the term of the lease to BMR. Deferred rent for this facility was approximately $1,419,000 as of March 31, 2015, and approximately $1,429,000 as of December 31, 2014.
	In March 2013, we entered into a commercial lease agreement with Prologis, L.P. (Prologis), as landlord, for office and research space in Sunnyvale, California. The facility is for operations that support our clinical development activities. The initial term of the lease is ten years and includes escalating rent payments which we recognize as lease operating expense on a straight-line basis. We will pay approximately $3,497,000 in aggregate rent over the term of the lease. As part of the lease, Prologis has agreed to provide us financial allowances to build initial tenant improvements, subject to customary terms and conditions relating to landlord-funded tenant improvements. The tenant improvements are recorded as leasehold improvement assets and amortized over the term of the lease. The financial allowances are treated as a lease incentive and recorded as deferred rent which is amortized as reductions to lease expense over the lease term. Deferred rent for this facility was approximately $391,000 as of March 31, 2015 and December 31, 2014.
	Operating Leases — United Kingdom
	In January 2011, we amended the existing lease agreements of our wholly-owned subsidiary, Stem Cell Sciences (U.K.) Ltd, effectively reducing our leased office and lab space. The lease by its terms was extended to September 30, 2013. In October 2013, we signed a new three-year lease agreement for the leased space and expect to pay rent of approximately GBP 53,000 per annum. StemCells, Inc. is the guarantor of Stem Cell Sciences (U.K.) Ltd.’s obligations under the existing lease. The lease includes an option for early termination of the lease agreement, which we exercised in February 2015. In December 2014, we sold our SC Proven reagent and cell culture business and as part of the wind-down of our business operations in UK, sublet our leased space from January 2014 to our opted early termination date of October 2014.
	With the exception of the operating leases discussed above, we have not entered into any significant off balance sheet financial arrangements and have not established any special purpose entities. We have not guaranteed any debts or commitments of other entities or entered into any options on non-financial assets.
	Contingencies
	In July 2006, we filed suit against Neuralstem, Inc. in the Federal District Court for the District of Maryland, alleging that Neuralstem’s activities violate claims in four of the patents we exclusively licensed at the time from NeuroSpheres, specifically U.S. Patent No. 6,294,346 (claiming the use of human neural stem cells for drug screening), U.S. Patent No. 7,101,709 (claiming the use of human neural stem cells for screening biological agents), U.S. Patent No. 5,851,832 (claiming methods for proliferating human neural stem cells), and U.S. Patent No. 6,497,872 (claiming methods for transplanting human neural stem cells). In May 2008, we filed a second patent infringement suit against Neuralstem and its two founders, Karl Johe and Richard Garr. In this suit, which we filed in the Federal District Court for the Northern District of California, we allege that Neuralstem’s activities infringe claims in two patents we exclusively licensed at the time from NeuroSpheres, specifically U.S. Patent No. 7,361,505 (claiming composition of matter of human neural stem cells derived from any source material) and U.S. Patent No. 7,115,418 (claiming methods for proliferating human neural stem cells). In addition, we allege various state law causes of action against Neuralstem arising out of its repeated derogatory statements to the public about our patent portfolio. Also in May 2008, Neuralstem filed suit against us and NeuroSpheres in the Federal District Court for the District of Maryland seeking a declaratory judgment that the ‘505 and ‘418 patents are either invalid or are not infringed by Neuralstem and that Neuralstem has not violated California state law. In August 2008, the California court transferred our lawsuit against Neuralstem to Maryland for resolution on the merits. In July 2009, the Maryland District Court granted our motion to consolidate these two cases with the litigation we initiated against Neuralstem in 2006. Fact discovery has concluded in the cases and, in December 2014, the Maryland federal court began the first phase of trial in order to address the sole question of whether we have legal standing to pursue our patent infringement claims against Neuralstem. We expect a ruling on the question of standing in the first half of 2015 and, if we are found to have standing to proceed, for the remainder of the trial to conclude in 2015.
	In addition to the actions described above, in April 2008, we filed an opposition to Neuralstem’s European Patent No. 0 915 968 (methods of isolating, propagating and differentiating CNS stem cells), because the claimed invention is believed by us to be unpatentable over prior art, including the patents we acquired from NeuroSpheres. In December 2010, the European Patent Office ruled that all composition claims in Neuralstem’s ‘968 European patent were invalid and unpatentable over prior art including several of the NeuroSpheres patents. Neuralstem appealed this decision but subsequently withdrew its appeal with prejudice.

Warrant_Liability

Warrant Liability	3 Months Ended
	Mar. 31, 2015
Text Block [Abstract]
Warrant Liability	Note 8. Warrant Liability
	We use various option pricing models, such as the Black-Scholes option pricing model and a Monte Carlo simulation model, to estimate fair value of warrants issued. In using these models, we make certain assumptions about risk-free interest rates, dividend yields, volatility, expected term of the warrants and other assumptions. Risk-free interest rates are derived from the yield on U.S. Treasury debt securities. Dividend yields are based on our historical dividend payments, which have been zero to date. Volatility is estimated from the historical volatility of our common stock as traded on NASDAQ. The expected term of the warrants is based on the time to expiration of the warrants from the date of measurement.
	In November 2009, we sold 1,000,000 units to institutional investors at a price of $12.50 per unit, for gross proceeds of $12,500,000. The units, each of which consisted of one share of common stock and a warrant to purchase 0.40 shares of common stock at an exercise price of $15.00 per share, were offered as a registered direct offering under a shelf registration statement previously filed with, and declared effective by, the SEC. We received total proceeds, net of offering expenses and placement agency fees, of approximately $11,985,000. We recorded the fair value of the warrants to purchase 400,000 shares of our common stock as a liability. The fair value of the warrant liability is revalued at the end of each reporting period, with the change in fair value of the warrant liability recorded as a gain or loss in our condensed consolidated statements of operations. The fair value of the warrants will continue to be classified as a liability until such time as the warrants are exercised, expire or an amendment of the warrant agreement renders these warrants to be no longer classified as a liability. The fair value of these warrants at March 31, 2015 was not significant.
	In December 2011, we raised gross proceeds of $10,000,000 through a public offering of 8,000,000 units and 8,000,000 Series B Warrants. The combination of units and Series B Warrants were sold at a public offering price of $1.25 per unit. Each Series B Warrant gave the holder the right to purchase one unit at an exercise price of $1.25 per unit and was exercisable until May 2, 2012, the 90th trading day after the date of issuance. Each unit consists of one share of our common stock and one Series A Warrant. Each Series A Warrant gives the holder the right to purchase one share of our common stock at an initial exercise price of $1.40 per share. The Series A Warrants are immediately exercisable upon issuance and will expire in December 2016. In 2012, an aggregate of 2,700,000 Series B Warrants were exercised. For the exercise of these warrants, we issued 2,700,000 shares of our common stock and 2,700,000 Series A Warrants. The remaining 5,300,000 Series B Warrants expired unexercised by their terms on May 2, 2012. In 2012, 2013 and 2014, an aggregate of 2,198,571, 384,534 and 1,180,015 Series A Warrants were exercised, respectively. For the exercise of these warrants, in 2012, 2013 and 2014, we issued 2,198,571, 384,534 and 1,180,015 shares of our common stock and received gross proceeds of approximately $3,078,000, $538,000 and $1,652,000, respectively. The shares were offered under our shelf registration statement previously filed with previously filed with, and declared effective by, the SEC.
	The assumptions used for the Monte Carlo simulation model to value the outstanding Series A Warrants at March 31, 2015 are as follows:
	Risk-free interest rate per year		0.45	%
	Expected volatility per year		57.8	%
	Expected dividend yield		0	%
	Expected life (years)		1.7
	The use of the Monte Carlo simulation model requires the input of additional subjective assumptions including the progress of our R&D programs and its affect on potential future financings.
	The following table is a summary of the changes in fair value of warrant liability for the Series A Warrants in 2015:
		Series A
		Number of			Fair value $
		Warrants
	Balance at December 31, 2014		6,936,880		$	1,684,551
	Changes in fair value		—			347,330
	Balance at March 31, 2015		6,936,880		$	2,031,881
	The following table is a summary of our warrant liability as of March 31, 2015:
	Warrants	Number Outstanding			Exercise Price ($)		Fair value
					per share
	Warrants issued in 2009		400,000			15	$	—
	Series A Warrants		6,936,880			1.4		2,031,881
	Total		7,336,880				$	2,031,881
	The fair value of the warrant liability is revalued at the end of each reporting period, with the change in fair value of the warrant liability recorded as a gain or loss in our condensed consolidated statements of operations. The fair value of the warrants will continue to be classified as a liability until such time as the warrants are exercised, expire or an amendment of the warrant agreement renders these warrants to be no longer classified as a liability.

Subsequent_Events

Subsequent Events	3 Months Ended
	Mar. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	Note 9. Subsequent Events
	In April 2015, we raised gross proceeds of approximately $25 million through a public offering of 35,715,000 Units. Each Unit consists of one share of our common stock and a warrant to purchase three-quarters of a share of our common stock. The warrants have an exercise price of $0.85 per share, are exercisable immediately, and will expire five years from the date of issuance. We also granted the underwriters a thirty day option to purchase up to an additional 5,357,250 shares of common stock and/or warrants to purchase up to an additional 4,017,938 shares of common stock to cover over-allotments, if any. The underwriters exercised the over-allotment option for the warrants and so, in April 2015, we issued warrants to purchase up to an additional 4,017,938 shares of common stock. The shares were offered under our effective shelf registration statement previously filed with the SEC.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Nature of Business	Nature of Business.
	StemCells, Inc., a Delaware corporation, is a biopharmaceutical company that operates in one segment, the research, development, and commercialization of stem cell therapeutics and related technologies.
	The accompanying financial data as of March 31, 2015 and for the three months ended March 31, 2015 and 2014 have been prepared by us, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States (U.S. GAAP) have been condensed or omitted pursuant to these rules and regulations. The December 31, 2014 condensed consolidated balance sheet was derived from audited financial statements, but does not include all disclosures required by U.S. GAAP. However, we believe that the disclosures are adequate to make the information presented not misleading. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and the notes thereto included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2014.
	We have incurred significant operating losses since inception. We expect to incur additional operating losses over the foreseeable future. We have very limited liquidity and capital resources and must obtain significant additional capital and other resources in order to provide funding for our product development efforts, the acquisition of technologies, businesses and intellectual property rights, preclinical and clinical testing of our products, pursuit of regulatory approvals, acquisition of capital equipment, laboratory and office facilities, establishment of production capabilities, general and administrative expenses and other working capital requirements. We rely on our cash reserves, proceeds from equity and debt offerings, credit facilities, proceeds from the transfer or sale of intellectual property rights, equipment, facilities or investments, government grants and funding from collaborative arrangements, to fund our operations. If we exhaust our cash reserves and are unable to obtain adequate financing, we may be unable to meet our operating obligations and we may be required to initiate bankruptcy proceedings. The financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that may result from the outcome of this uncertainty.
Principles of Consolidation	Principles of Consolidation
	The condensed consolidated financial statements include the accounts of StemCells, Inc., and our wholly-owned subsidiaries, including StemCells California, Inc., Stem Cell Sciences Holdings Ltd, and Stem Cell Sciences (UK) Ltd (SCS). All significant intercompany accounts and transactions have been eliminated
Reclassifications	Reclassifications
	Certain reclassifications have been made to the prior year financial statements in order to conform to the current year’s presentation.
Use of Estimates	Use of Estimates
	The preparation of financial statements in conformity with U.S. GAAP requires management to make judgments, assumptions and estimates that affect the amounts reported in our condensed consolidated financial statements and accompanying notes. Actual results could differ materially from these estimates.
	Significant estimates include the following:
	•	the grant date fair value of stock-based awards recognized as compensation expense (see Note 5, “Stock-Based Compensation”);
	•	the fair value of warrants recorded as a liability (see Note 8, “Warrant Liability”).
Discontinued Operations	Discontinued Operations
	The results of operations of a business that either has been disposed of or is classified as held-for-sale are reported in discontinued operations if the operations and cash flows of the component have been or will be eliminated from our ongoing operations as a result of the disposal transaction and we will not have any significant continuing involvement in the operations of the component after the disposal transaction. We present the operations of a business that meet this criteria as a discontinued operation, and retrospectively reclassify operating results for all prior periods presented. In the fourth quarter of 2014, as part of our strategy to focus on our clinical operations, we sold our SC Proven reagent and cell culture business and wound-down our business operations at our Stem Cell Sciences Subsidiary in Cambridge, UK (SCS). The results of operations for this component have been classified as discontinued operations for all periods in our Consolidated Statement of Operations.
Financial Instruments	Financial Instruments
	Cash and Cash Equivalents
	Cash equivalents are money market accounts, money market funds and investments with maturities of 90 days or less from the date of purchase.
	Receivables
	Our receivables generally consist of interest income on our financial instruments and royalties due from licensing agreements.
	Warrant Liability
	We account for our warrants in accordance with U.S. GAAP which defines how freestanding contracts that are indexed to and potentially settled in a company’s own stock should be measured and classified. Authoritative accounting guidance prescribes that only warrants issued by us under contracts that cannot be net-cash settled, and are both indexed to and settled in our common stock, can be classified as equity. As part our November 2009 financing, we issued warrants with five year terms to purchase 400,000 shares of our common stock at $15.00 per share. As part of our December 2011 financing, we issued Series A Warrants with a five year term to purchase 8,000,000 shares at $1.40 per share and Series B Warrants with a ninety trading day term to purchase 8,000,000 units at $1.25 per unit. Each unit underlying the Series B Warrants consisted of one share of our common stock and one Series A Warrant. In the first and second quarter of 2012, an aggregate of 2,700,000 Series B Warrants were exercised. For the exercise of these warrants, we issued 2,700,000 shares of our common stock and 2,700,000 Series A Warrants. The remaining 5,300,000 Series B Warrants expired unexercised by their terms on May 2, 2012. As terms of the warrants issued in 2009, as well as the Series A and Series B Warrants, do not meet the specific conditions for equity classification, we are required to classify the fair value of these warrants as a liability, with subsequent changes in fair value to be recorded as income (loss) due to change in fair value of warrant liability. The fair value of the warrants issued in the 2009 financing is determined using the Black-Scholes-Merton (Black-Scholes) option pricing model and the fair value of the Series A and Series B Warrants is determined using a Monte Carlo simulation model (see Note 8, “Warrant Liability”). The fair value is affected by changes in inputs to these models including our stock price, expected stock price volatility, the contractual term, and the risk-free interest rate. The use of a Monte Carlo simulation model requires input of additional assumptions including the progress of our R&D programs and its affect on potential future financings. We will continue to classify the fair value of the warrants as a liability until the warrants are exercised, expire or are amended in a way that would no longer require these warrants to be classified as a liability. The estimated fair value of our warrant liability at March 31, 2015, was approximately $2,032,000.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets
	Goodwill and intangible assets deemed to have indefinite lives are not amortized but are subject to annual impairment tests. If the assumptions and estimates used to allocate the purchase price are not correct, or if business conditions change, purchase price adjustments or future asset impairment charges could be required. We test goodwill for impairment on an annual basis or more frequently if we believe indicators of impairment exist. Impairment evaluations involve management estimates of asset useful lives and future cash flows. Significant management judgment is required in the forecasts of future operating results that are used in the evaluations, and it is possible, even likely, that the plans and estimates used may be incorrect. On April 1, 2009, we acquired the operations of SCS for an aggregate purchase price of approximately $5,135,000. Approximately 42% of the purchase price was allocated to Goodwill. The acquired operations included proprietary cell technologies relating to embryonic stem cells, induced pluripotent stem (iPS) cells, and tissue-derived (adult) stem cells; expertise and infrastructure for providing cell-based assays for drug discovery; a cell culture products business; and an intellectual property portfolio with claims relevant to cell processing, reprogramming and manipulation, as well as to gene targeting and insertion. In the fourth quarter of 2014, as part of our strategy to focus on our clinical operations, we sold our SC Proven reagent and cell culture business and wound-down our business operations at our SCS Subsidiary in Cambridge, UK. We also determined that we could not predict the future cash flows if any from the intellectual property portfolio acquired. Based on these factors, we determined that the Goodwill related to the acquisition was impaired and wrote off its carrying value of approximately $1,910,000 in the fourth quarter of 2014.
	Prior to fiscal year 2001, we capitalized certain patent costs, which are being amortized over the estimated life of the patent and would be expensed at the time such patents are deemed to have no continuing value. Since 2001, all patent costs are expensed as incurred. License costs are capitalized and amortized over the estimated life of the related license agreement.
Revenue Recognition	Revenue Recognition
	We currently recognize revenue resulting from the licensing and use of our technology and intellectual property. Licensing agreements may contain multiple elements, such as upfront fees, payments related to the achievement of particular milestones and royalties. Revenue from upfront fees for licensing agreements that contain multiple elements are generally deferred and recognized on a straight-line basis over the term of the agreement. Fees associated with substantive at risk performance-based milestones are recognized as revenue upon completion of the scientific or regulatory event specified in the agreement, and royalties received are recognized as earned. Revenue from licensing agreements is recognized net of a fixed percentage due to licensors as royalties.
Stock-Based Compensation	Stock-Based Compensation
	Compensation expense for stock-based payment awards to employees is based on their grant date fair value as calculated and amortized over their vesting period. See Note 5, “Stock-Based Compensation” for further information.
	We use the Black-Scholes model to calculate the fair value of stock-based awards.
Per Share Data	Per Share Data
	Basic net income or loss per share is computed by dividing net income or loss by the weighted average number of shares of common stock outstanding during the period. Diluted net income or loss per share is computed based on the weighted average number of shares of common stock and other dilutive securities. To the extent these securities are anti-dilutive, they are excluded from the calculation of diluted earnings per share.
	The following is a reconciliation of the numerators and denominators of the basic and diluted net loss per share computations:
		Three months ended March 31,
		2015			2014
	Net loss from continuing operations	$	(9,350,701	)	$	(7,562,528	)
	Net loss from discontinued operations		—			(57,728	)
	Net loss	$	(9,350,701	)	$	(7,620,256	)
	Weighted average shares outstanding used to compute basic and diluted net income or loss per share		69,219,964			55,343,877
	per share
	Basic and diluted net loss per share from continuing operations	$	(0.14	)	$	(0.14	)
	Basic and diluted net loss per share from discontinued operations		—			—
	Basic and diluted net loss per share	$	(0.14	)	$	(0.14	)
	The following outstanding potentially dilutive securities were excluded from the computation of diluted net income or loss per share because the effect would have been anti-dilutive as of March 31:
		2015			2014
	Options		276,229			381,851
	Restricted stock units		9,984,519			3,144,940
	Warrants		23,478,181			16,267,659
	Total		33,738,929			19,794,450
Comprehensive Income (Loss)	Comprehensive Income (Loss)
	Comprehensive income (loss) is comprised of net income or loss and other comprehensive income or loss (OCL). OCL includes certain changes in stockholders’ equity that are excluded from net income or loss. Specifically, when applicable, we include in OCL changes in unrealized gains and losses on foreign currency translations. Accumulated other comprehensive income was $32,948 as of March 31, 2015, and accumulated other comprehensive income was $65,390, as of December 31, 2014.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Basic and Diluted Net Loss per Share Computations	The following is a reconciliation of the numerators and denominators of the basic and diluted net loss per share computations:
		Three months ended March 31,
		2015			2014
	Net loss from continuing operations	$	(9,350,701	)	$	(7,562,528	)
	Net loss from discontinued operations		—			(57,728	)
	Net loss	$	(9,350,701	)	$	(7,620,256	)
	Weighted average shares outstanding used to compute basic and diluted net income or loss per share		69,219,964			55,343,877
	per share
	Basic and diluted net loss per share from continuing operations	$	(0.14	)	$	(0.14	)
	Basic and diluted net loss per share from discontinued operations		—			—
	Basic and diluted net loss per share	$	(0.14	)	$	(0.14	)
Outstanding Options, Warrants and Restricted Stock Units	The following outstanding potentially dilutive securities were excluded from the computation of diluted net income or loss per share because the effect would have been anti-dilutive as of March 31:
		2015			2014
	Options		276,229			381,851
	Restricted stock units		9,984,519			3,144,940
	Warrants		23,478,181			16,267,659
	Total		33,738,929			19,794,450

Financial_Instruments_Tables

Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Cash and Cash Equivalents Held in Investment Portfolio	The following table summarizes the fair value of our cash and cash equivalents held in our current investment portfolio:
		Amortized		Gross		Gross		Fair Value
		Cost		Unrealized		Unrealized
				Gains		(Losses)
	March 31, 2015
	Cash	$	2,655,834	$	—	$	—	$	2,655,834
	Cash equivalents		11,490,067		—		—		11,490,067
	Total cash and cash equivalents	$	14,145,901	$	—	$	—	$	14,145,901
		Amortized		Gross		Gross		Fair Value
		Cost		Unrealized		Unrealized
				Gains		(Losses)
	December 31, 2014
	Cash	$	1,398,928	$	—	$	—	$	1,398,928
	Cash equivalents		23,588,675		—		—		23,588,675
	Total cash and cash equivalents	$	24,987,603	$	—	$	—	$	24,987,603

Fair_Value_Measurement_Tables

Fair Value Measurement (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities Measured at Fair Value	The following table presents financial assets and liabilities measured at fair value as of March 31, 2015:
		Fair Value Measurement
		at Report Date Using
		Quoted Prices			Significant		Unobservable		As of
		in Active Markets			Other		Inputs		March 31,
		for			Observable		(Level 3)		2015
		Identical Assets			Inputs
		(Level 1)			(Level 2)
	Financial assets:
	Cash equivalents:
	Money market funds	$	321,444		$	—	$	—	$	321,444
	U.S. Treasury debt obligations		11,168,623			—		—		11,168,623
	Total financial assets	$	11,490,067		$	—	$	—	$	11,490,067
	Financial liabilities:
	Loan payable net of discounts		—			—		13,372,796		13,372,796
	Warrant liabilities		—			—		2,031,881		2,031,881
	Total financial liabilities	$	—		$	—	$	15,404,677	$	15,404,677
Roll Forward for Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3)	The following table presents a roll forward for liabilities measured at fair value using significant unobservable inputs (Level 3) for 2015:
		Warrant
		liabilities
	Balance at December 31, 2014	$	1,684,551
	Add change in fair value of warrants		347,330
	Balance at March 31, 2015	$	2,031,881
		Loan payable net of discounts
	Balance at December 31, 2014	$	15,020,417
	Add amortization of discount		34,043
	Less repayments of principal		(1,681,664	)
	Balance at March 31, 2015	$	13,372,796
	Current portion		4,097,837
	Non-current portion		9,274,959
	Balance at March 31, 2015	$	13,372,796

Intangible_Assets_Tables

Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Components of Intangible Assets	The components of our intangible assets at March 31, 2015 are summarized below:
	Intangible Asset Class	Cost		Accumulated			Net		Weighted
				Amortization			Carrying		Average
							Amount		Amortization
									Period
	Patents	$	1,243,612	$	(907,585	)	$	336,027		17 years
Expected Future Annual Amortization Expense	The expected future annual amortization expense for each of the next five years based on current balances of our intangible assets is approximately as follows:
	For the year ending December 31:
	2016	$	75,496
	2017	$	54,923
	2018	$	27,978
	2019	$	27,978
	2020	$	26,594

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Expense	Our stock-based compensation expense for the three months ended March 31 was as follows:
			Three months ended
			March 31,
			2015			2014
	Research and development expense		$	583,669		$	186,293
	General and administrative expense			725,225			334,813
	Total stock-based compensation		$	1,308,894		$	521,106
	Effect on basic and diluted net loss per share		$	(0.02	)	$	(0.01	)
Stock Option Activity	A summary of our stock option activity for the three months ended March 31, 2015 is as follows:
			Number of options			Weighted-average
						exercise price ($) per share
	Outstanding options at December 31, 2014			302,729			18.18
	Granted			—			—
	Exercised			—			—
	Cancelled			(26,500	)		13.18
	Outstanding options at March 31, 2015			276,229			18.66
Summary of Changes in Restricted Stock Unit Activity	A summary of changes in our restricted stock units for the three months ended March 31, 2015 is as follows:
			Number of RSUs			Weighted Average
						Grant Date
						Fair Value ($)
	Outstanding at December 31, 2014			3,374,940			1.55
	Granted(1)			7,290,768			1.11
	Vested and exercised			(634,090	)		1.21
	Cancelled			(47,100	)		1.51
	Outstanding at March 31, 2015			9,984,518			1.25
	-1	349,518 of these restricted stock units vest and convert into shares of our common stock after one year from the date of grant. 2,586,750 of these restricted stock units will vest and convert into shares of our common stock over a three year period from the date of grant; one-third of the award will vest on each grant date anniversary following the grant. 4,354,500 of these restricted stock units are performance based and vest on achievement of predefined milestones.

Loan_Payable_Tables

Loan Payable (Tables)	3 Months Ended
	Mar. 31, 2015
Summary of Changes in Carrying Value of Loans Payable	The following table is a summary of the changes in the carrying value of our loans payable for the three months ended March 31, 2015:
		Silicon Valley			CIRM Loan			Total
		Bank Loan
	Carrying value of loan payable at 12/31/2014 (current and non-current)	$	5,424,610		$	9,595,807		$	15,020,417
	Repayment of principal		(1,002,498	)		(679,166	)		(1,681,664	)
	Accretion of discount		34,043			—			34,043
	Carrying value of loan payable at 3/31/2015 (current and non-current)	$	4,456,155		$	8,916,641		$	13,372,796
	Carrying value of loan payable, current portion	$	4,097,837		$	—		$	4,097,837
	Carrying value of loan payable, non-current portion		358,318			8,916,641			9,274,959
	Total loan payable at 03/31/2015	$	4,456,155		$	8,916,641		$	13,372,796
Silicon Valley Bank Loan Agreement Warrant [Member]
Assumptions Used for Black-Scholes Option Pricing Model	We estimated the fair value of the warrant to be approximately $388,000 using the Black-Scholes option pricing model with the following assumptions:
	Expected life (years)		10
	Risk-free interest rate		1.9	%
	Expected volatility		88.1	%
	Expected dividend yield		0	%

Warrant_Liability_Tables

Warrant Liability (Tables)	3 Months Ended
	Mar. 31, 2015
Text Block [Abstract]
Assumptions Used for Simulation Model	The assumptions used for the Monte Carlo simulation model to value the outstanding Series A Warrants at March 31, 2015 are as follows:
	Risk-free interest rate per year		0.45	%
	Expected volatility per year		57.8	%
	Expected dividend yield		0	%
	Expected life (years)		1.7
Summary of Changes in Fair Value of Warrant Liability	The following table is a summary of the changes in fair value of warrant liability for the Series A Warrants in 2015:
		Series A
		Number of			Fair value $
		Warrants
	Balance at December 31, 2014		6,936,880		$	1,684,551
	Changes in fair value		—			347,330
	Balance at March 31, 2015		6,936,880		$	2,031,881
Summary of Warrant Liability	The following table is a summary of our warrant liability as of March 31, 2015:
	Warrants	Number Outstanding			Exercise Price ($)		Fair value
					per share
	Warrants issued in 2009		400,000			15	$	—
	Series A Warrants		6,936,880			1.4		2,031,881
	Total		7,336,880				$	2,031,881

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended		1 Months Ended		12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Nov. 30, 2009	Dec. 31, 2011	Dec. 31, 2012	Apr. 01, 2009
	Segment
Class of Warrant or Right [Line Items]
Number of segments	1
Maturity period for market accounts, money market funds and investments	90 days
Common stock per unit	$1
Warrants issued per unit	$1
Value of patent	$0
Accumulated other comprehensive income	32,948	65,390
Stem Cell Sciences Holdings Ltd [Member]
Class of Warrant or Right [Line Items]
Aggregate purchase price						5,135,000
Percentage of purchase price allocated to goodwill		42.00%
Impairment of Goodwill		1,910,000
Outstanding Warrants [Member]
Class of Warrant or Right [Line Items]
Fair value of warrant liability	$2,032,000
November 2009 Financing [Member]
Class of Warrant or Right [Line Items]
Exercise price of warrants	$15
November 2009 Financing [Member] | Outstanding Warrants [Member]
Class of Warrant or Right [Line Items]
Term of warrant			5 years
November 2009 Financing [Member] | Common Stock [Member]
Class of Warrant or Right [Line Items]
Number of securities callable by warrants			400,000
Exercise price of warrants			15
December 2011 Financing [Member] | Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Number of securities callable by warrants				8,000,000
Term of warrant				5 years
Number of warrants issued upon Series B warrants exercise					2,700,000
December 2011 Financing [Member] | Series B Warrants [Member]
Class of Warrant or Right [Line Items]
Number of securities callable by warrants				8,000,000
Exercise price of warrants				1.25
Term of warrant				90 days
Number of warrants exercised					2,700,000
Number of warrants expired					5,300,000
December 2011 Financing [Member] | Common Stock [Member]
Class of Warrant or Right [Line Items]
Number of shares issued upon Series B warrants exercise					2,700,000
December 2011 Financing [Member] | Common Stock [Member] | Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Exercise price of warrants				1.4

Summary_of_Significant_Account4

Summary of Significant Accounting Policies - Basic and Diluted Net Loss per Share Computations (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Accounting Policies [Abstract]
Net loss from continuing operations	($9,350,701)	($7,562,528)
Net loss from discontinued operations		-57,728
Net loss	($9,350,701)	($7,620,256)
Weighted average shares outstanding used to compute basic and diluted net income or loss per share	69,219,964	55,343,877
Basic and diluted net loss per share from continuing operations	($0.14)	($0.14)
Basic and diluted net loss per share from discontinued operations	$0	$0
Basic and diluted net loss per share	($0.14)	($0.14)

Summary_of_Significant_Account5

Summary of Significant Accounting Policies - Outstanding Options, Warrants and Restricted Stock Units (Detail)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Class of Stock [Line Items]
Outstanding options, warrants and restricted stock units	33,738,929	19,794,450
Options [Member]
Class of Stock [Line Items]
Outstanding options, warrants and restricted stock units	276,229	381,851
Restricted stock units [Member]
Class of Stock [Line Items]
Outstanding options, warrants and restricted stock units	9,984,519	3,144,940
Outstanding Warrants [Member]
Class of Stock [Line Items]
Outstanding options, warrants and restricted stock units	23,478,181	16,267,659

Financial_Instruments_Cash_and

Financial Instruments - Cash and Cash Equivalents Held in Investment Portfolio (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$14,145,901	$24,987,603
Gross Unrealized Gains	0	0
Gross Unrealized (Losses)	0	0
Fair Value	14,145,901	24,987,603
Cash [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,655,834	1,398,928
Gross Unrealized Gains	0	0
Gross Unrealized (Losses)	0	0
Fair Value	2,655,834	1,398,928
Cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,490,067	23,588,675
Gross Unrealized Gains	0	0
Gross Unrealized (Losses)	0	0
Fair Value	$11,490,067	$23,588,675

Fair_Value_Measurement_Financi

Fair Value Measurement - Financial Assets and Liabilities Measured at Fair Value (Detail) (USD $)	Mar. 31, 2015
Outstanding Warrants [Member]
Financial liabilities:
Total financial liabilities	$2,031,881
Fair Value, Measurements [Member]
Financial assets:
Total financial assets	11,490,067
Financial liabilities:
Total financial liabilities	15,404,677
Fair Value, Measurements [Member] | Money market funds [Member] | Cash equivalents [Member]
Financial assets:
Total financial assets	321,444
Fair Value, Measurements [Member] | U.S. Treasury debt obligations [Member] | Cash equivalents [Member]
Financial assets:
Total financial assets	11,168,623
Fair Value, Measurements [Member] | Loan Payable [Member]
Financial liabilities:
Total financial liabilities	13,372,796
Fair Value, Measurements [Member] | Outstanding Warrants [Member]
Financial liabilities:
Total financial liabilities	2,031,881
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements [Member]
Financial assets:
Total financial assets	11,490,067
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements [Member] | Money market funds [Member] | Cash equivalents [Member]
Financial assets:
Total financial assets	321,444
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements [Member] | U.S. Treasury debt obligations [Member] | Cash equivalents [Member]
Financial assets:
Total financial assets	11,168,623
Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements [Member]
Financial liabilities:
Total financial liabilities	15,404,677
Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements [Member] | Loan Payable [Member]
Financial liabilities:
Total financial liabilities	13,372,796
Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements [Member] | Outstanding Warrants [Member]
Financial liabilities:
Total financial liabilities	$2,031,881

Fair_Value_Measurement_Roll_Fo

Fair Value Measurement - Roll Forward for Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3) (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Add change in fair value of warrants	($347,330)	($326,624)
Less repayments of principal	-1,681,664
Outstanding Warrants [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at December 31, 2014	1,684,551
Add change in fair value of warrants	347,330
Balance at March 31, 2015	2,031,881
Balance at March 31, 2015	2,031,881
Loan Payable [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at December 31, 2014	15,020,417
Add amortization of discount	34,043
Less repayments of principal	-1,681,664
Balance at March 31, 2015	13,372,796
Current portion	4,097,837
Non-current portion	9,274,959
Balance at March 31, 2015	$13,372,796

Intangible_Assets_Components_o

Intangible Assets - Components of Intangible Assets (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Net Carrying Amount	$336,027	$356,889
Patents [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Cost	1,243,612
Accumulated Amortization	-907,585
Net Carrying Amount	$336,027
Weighted-Average Amortization Period	17 years

Intangible_Assets_Additional_I

Intangible Assets - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Amortization expense	$21,000
Expected amortization expense for the year ended December 31, 2015	$83,000

Intangible_Assets_Expected_Fut

Intangible Assets - Expected Future Annual Amortization Expense (Detail) (USD $)	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
2016	$75,496
2017	54,923
2018	27,978
2019	27,978
2020	$26,594

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended	0 Months Ended	3 Months Ended
	Mar. 31, 2015	Dec. 20, 2013	Mar. 31, 2014	Dec. 31, 2014
	Incentive_Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plans	2
Shares authorized	225,000,000			225,000,000
Total unrecognized compensation expense	$9,884,000
Vesting period	2 years 4 months 24 days
Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized	7,856,374
Annual increase in number of shares of common stock	4.00%
Aggregate limit of shares issuable to incentive stock option awards	3,000,000
Initial grant of stock-based compensation in shares		6,000,000
Increase in percentage of outstanding number of shares of common stock		4.00%
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vested grant yearly	25.00%
Percentage of vested grant monthly	75.00%
Term of years	10 years
Vesting period of grant date	3 years
Exercise price	$20
Number of SARs, outstanding	110,593		110,593
Number of SARs, Granted	0
Number of SARs, Exercised	0
Number of SARs, Forfeited	0
Reduced compensation expense	$0		$0
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units vest and convert into shares of our common stock	1 year
Restricted Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of years	10 years
Vesting period of grant date	3 years
Restricted Stock [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of grant date	1 year
Restricted Stock Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units vest and convert into shares of our common stock	4 years
Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vested grant yearly	25.00%
Percentage of vested grant monthly	75.00%
Term of years	4 years
Unexercised vested option forfeiture	3 months
Options [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of years	10 years
Vesting period of grant date	3 years

StockBased_Compensation_StockB

Stock-Based Compensation - Stock-Based Compensation Expense (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense and effect on net loss	$1,308,894	$521,106
Effect on basic and diluted net loss per share	($0.02)	($0.01)
Research and development expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense and effect on net loss	583,669	186,293
Selling, general and administrative expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense and effect on net loss	$725,225	$334,813

StockBased_Compensation_Stock_

Stock-Based Compensation - Stock Option Activity (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of options, Beginning balance	302,729
Number of options, Granted	0
Number of options, Exercised	0
Number of options, Cancelled	-26,500
Number of options, Ending balance	276,229
Weighted-average exercise price per share, Beginning balance	$18.18
Weighted-average exercise price per share, Granted	$0
Weighted-average exercise price per share, Exercised	$0
Weighted-average exercise price per share, Cancelled	$13.18
Weighted-average exercise price per share, Ending balance	$18.66

StockBased_Compensation_Summar

Stock-Based Compensation - Summary of Changes in Restricted Stock Unit Activity (Detail) (Restricted stock units [Member], USD $)	3 Months Ended
	Mar. 31, 2015
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of RSUs, Beginning balance	3,374,940
Number of RSUs, Granted	7,290,768
Number of RSUs, Vested	-634,090
Number of RSUs, Cancelled	-47,100
Number of RSUs, Ending balance	9,984,518
Weighted Average Grant Date Fair Value, Beginning balance	$1.55
Weighted Average Grant Date Fair Value, Granted	$1.11
Weighted Average Grant Date Fair Value, Vested	$1.21
Weighted Average Grant Date Fair Value, Cancelled	$1.51
Weighted Average Grant Date Fair Value, Ending balance	$1.25

StockBased_Compensation_Summar1

Stock-Based Compensation - Summary of Changes in Restricted Stock Unit Activity (Parenthetical) (Detail)	3 Months Ended
	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units vest description	349,518 of these restricted stock units vest and convert into shares of our common stock after one year from the date of grant. 2,586,750 of these restricted stock units will vest and convert into shares of our common stock over a three year period from the date of grant; one-third of the award will vest on each grant date anniversary following the grant. 4,354,500 of these restricted stock units are performance based and vest on achievement of predefined milestones.
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted units would vest over vesting period	349,518
Restricted stock units vest and convert into shares of our common stock	1 year
Restricted Stock Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted units would vest over vesting period	2,586,750
Restricted stock units vest and convert into shares of our common stock	3 years
Restricted stock units vested description after specified period	0.3333
Performance Based Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted units vest and convert into common stock over next fiscal year	4,354,500

Loan_Payable_Additional_Inform

Loan Payable - Additional Information (Detail) (USD $)	1 Months Ended		3 Months Ended	14 Months Ended
	Feb. 28, 2015	Apr. 30, 2013	Mar. 31, 2015	Aug. 31, 2014
Debt Instrument [Line Items]
Cash discount			$100,000
Loan term			3 years
Annual interest rate on loan			6.00%
Period of loan subject to interest payments only			6 months
Period of loan subject to principal and interest payments			30 months
Final fee payment at the end of loan term			1,000,000
Proceeds received under loan agreement			9,900,000
Initial carrying amount assigned to loan, net of discount			9,512,000
Fair value allocated to warrant			388,000
Note issuance costs			117,000
Deferred financing costs, discount and accretion percentage			9.00%
CIRM [Member]
Debt Instrument [Line Items]
Approval of fund by California Institute for Regenerative Medicine (CIRM)		19,300,000
Aggregate proceeds from disbursement of the loan				9,600,000
Forgiveness of loan principal			8,917,000
Accrued interest forgiven			243,000
Repayment of aggregate loan proceeds received	679,000
Silicon Valley Bank Loan Agreement Warrant [Member]
Debt Instrument [Line Items]
Term of warrant expiration			10 years
Exercise price of warrant			$1.70
Warrant expiration period			Apr-23
Silicon Valley Bank Loan Agreement Warrant [Member] | Common Stock [Member]
Debt Instrument [Line Items]
Number of shares of common stock acquired using warrant			293,531
Silicon Valley Bank [Member]
Debt Instrument [Line Items]
Proceeds from loan		9,900,000
Cash discount		$100,000

Loan_Payable_Assumptions_Used_

Loan Payable - Assumptions Used for Black-Scholes Option Pricing Model (Detail) (Silicon Valley Bank Loan Agreement Warrant [Member])	3 Months Ended
	Mar. 31, 2015
Silicon Valley Bank Loan Agreement Warrant [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Expected life (years)	10 years
Risk-free interest rate	1.90%
Expected volatility	88.10%
Expected dividend yield	0.00%

Loan_Payable_Summary_of_Change

Loan Payable - Summary of Changes in Carrying Value of Loans Payable (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Carrying value of loan payable (current and non-current) Beginning Balance	$13,372,796	$15,020,417
Repayment of principal	-1,681,664
Accretion of discount	34,043
Carrying value of loan payable (current and non-current) Ending Balance	13,372,796	15,020,417
Carrying value of loan payable, current portion	4,097,837	4,686,388
Carrying value of loan payable, non-current portion	9,274,959	10,334,029
Total loan payable	13,372,796	15,020,417
CIRM [Member]
Debt Instrument [Line Items]
Carrying value of loan payable (current and non-current) Beginning Balance	8,916,641	9,595,807
Repayment of principal	-679,166
Carrying value of loan payable (current and non-current) Ending Balance	8,916,641	9,595,807
Carrying value of loan payable, non-current portion	8,916,641
Total loan payable	8,916,641	9,595,807
Silicon Valley Bank [Member]
Debt Instrument [Line Items]
Carrying value of loan payable (current and non-current) Beginning Balance	4,456,155	5,424,610
Repayment of principal	-1,002,498
Accretion of discount	34,043
Carrying value of loan payable (current and non-current) Ending Balance	4,456,155	5,424,610
Carrying value of loan payable, current portion	4,097,837
Carrying value of loan payable, non-current portion	358,318
Total loan payable	$4,456,155	$5,424,610

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail)

1 Months Ended

3 Months Ended

1 Months Ended

1 Months Ended

3 Months Ended

1 Months Ended

Mar. 31, 2015

Jul. 31, 2006

Mar. 31, 2015

Dec. 31, 2014

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2013

Mar. 31, 2015

Dec. 31, 2014

Oct. 31, 2013

Mar. 31, 2015

Dec. 31, 2010

Mar. 31, 2015

Dec. 31, 2014

USD ($)

Claim

USD ($)

USD ($)

Pilot Manufacturing Facility [Member]

Cell Processing Facility [Member]

Prologis, L.P [Member]

Prologis, L.P [Member]

Prologis, L.P [Member]

Stem Cell Sciences (U.K.) Ltd [Member]

Stem Cell Sciences (U.K.) Ltd [Member]

BMR-Gateway Boulevard LLC [Member]

BMR-Gateway Boulevard LLC [Member]

BMR-Gateway Boulevard LLC [Member]

sqft

sqft

USD ($)

USD ($)

USD ($)

GBP (£)

USD ($)

USD ($)

USD ($)

Commitment And Contingencies [Line Items]

Proceeds from the issuance of industrial revenue bonds

$5,000,000

Period of maturity

2014-08

Facility square-feet

21,000

3,000

Proceeds from sale of property, plant and equipment

149,000

148,713

Term of lease

10 years

3 years

11 years 6 months

Rent over term of lease

3,497,000

17,869,000

Deferred rent under sublease agreement

98,791

98,791

85,925

391,000

391,000

1,419,000

1,429,000

Rental payments under the existing lease

£ 53,000

Lease termination date

31-Oct-14

Number of patients violate claims of Neuralstem's activities

4

Warrant_Liability_Additional_I

Warrant Liability - Additional Information (Detail) (USD $)	12 Months Ended			1 Months Ended	12 Months Ended	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Nov. 30, 2009	Dec. 31, 2011	Mar. 31, 2015
Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Exercise price of warrants						1.4
Proceeds from sale of stock	$1,652,000	$538,000	$3,078,000
November 2009 Financing [Member]
Class of Warrant or Right [Line Items]
Number of units sold to investors				1,000,000
Price per unit				$12.50
Gross proceeds from units sold to investors				12,500,000
Exercise price of warrants						15
Proceeds from sale of stock				11,985,000
November 2009 Financing [Member] | Common Stock [Member]
Class of Warrant or Right [Line Items]
Number of securities callable by each warrant or right warrants				0.4
Exercise price of warrants				$15
Number of securities callable by warrants				400,000
Number of warrants in each unit sold to institutional investors				1
December 2011 Financing [Member]
Class of Warrant or Right [Line Items]
Price per unit					$1.25
Proceeds from issuance of common stock and warrants					$10,000,000
Number of Series A warrants in each unit issued in public offering					1
December 2011 Financing [Member] | Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Number of securities callable by warrants					8,000,000
Number of warrants exercised	1,180,015	384,534	2,198,571
Number of shares issued upon warrants exercise			2,700,000
December 2011 Financing [Member] | Series B Warrant [Member]
Class of Warrant or Right [Line Items]
Number of securities callable by warrants					8,000,000
Term of warrant					90 days
Warrant expiration						2012-May-02
Number of warrants exercised			2,700,000
Number of warrants expired						5,300,000
December 2011 Financing [Member] | Common Stock [Member]
Class of Warrant or Right [Line Items]
Number of shares issued upon warrants exercise			2,700,000
Number of shares issued upon warrants exercise	1,180,015	384,534	2,198,571
December 2011 Financing [Member] | Common Stock [Member] | Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Exercise price of warrants					$1.40
December 2011 Financing [Member] | Capital Units [Member] | Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Number of securities callable by each warrant or right warrants					1
December 2011 Financing [Member] | Capital Units [Member] | Series B Warrant [Member]
Class of Warrant or Right [Line Items]
Number of securities callable by each warrant or right warrants					1
Warrant expiration						Dec-16

Warrant_Liability_Assumptions_

Warrant Liability - Assumptions Used for Monte Carlo Simulation Model (Detail) (Series A Warrants [Member])	3 Months Ended
	Mar. 31, 2015
Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Risk-free interest rate per year	0.45%
Expected volatility per year	57.80%
Expected dividend yield	0.00%
Expected life (years)	1 year 8 months 12 days

Warrant_Liability_Summary_of_C

Warrant Liability - Summary of Changes in Fair Value of Warrant Liability (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015
Class of Warrant or Right [Line Items]
Number of Warrants, ending balance	7,336,880
Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Number of Warrants, beginning balance	6,936,880
Number of Warrants, changes in fair value	0
Number of Warrants, ending balance	6,936,880
Fair value of warrant liability, beginning balance	$1,684,551
Fair value, changes in fair value at period end	347,330
Fair value of warrant liability, ending balance	$2,031,881

Warrant_Liability_Summary_of_W

Warrant Liability - Summary of Warrant Liability (Detail) (USD $)	Mar. 31, 2015
Class of Warrant or Right [Line Items]
Number Outstanding	7,336,880
Outstanding Warrants [Member]
Class of Warrant or Right [Line Items]
Fair Value	2,031,881
Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Number Outstanding	6,936,880
Exercise Price per share	1.4
Series A Warrants [Member] | Outstanding Warrants [Member]
Class of Warrant or Right [Line Items]
Fair Value	2,031,881
November 2009 Financing [Member]
Class of Warrant or Right [Line Items]
Number Outstanding	400,000
Exercise Price per share	15

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (Subsequent Events [Member], USD $)	1 Months Ended
	Apr. 30, 2015
Subsequent Event [Line Items]
Proceeds from issuance of common stock and warrants	$25,000,000
Common stock issued in public offering	35,715,000
Exercise price of warrants	$0.85
Warrant expiration period	5 years
Over-Allotments [Member]
Subsequent Event [Line Items]
Common stock issued in public offering	5,357,250
Number of securities callable by warrants	4,017,938
Warrants issued for purchase of additional common shares	4,017,938
Common Stock [Member]
Subsequent Event [Line Items]
Number of securities callable by each warrant or right warrants	0.75