Approval of fund to Collaborators

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- Definition

Carrying Value Of Purchased Loans

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- Definition

Class Of Warrant Or Right Exercise Period Of Warrants Or Rights

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- Definition

Debt Instrument Amortized Discount Percentage

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- Definition

Debt Instrument Period During Which Loan Is Subject To Interest Only Payments

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- Definition

Debt Instrument Period During Which Loan Is Subject To Principal And Interest Payments

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- Definition

Fair Value Allocated To Warrant

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- Definition

Loan Fees

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- Definition

Expiration date of warrants

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No definition available.

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- Definition

Exercise price per share or per unit of warrants or rights outstanding.

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- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

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-Name Accounting Standards Codification

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- Definition

Decrease for amounts of indebtedness forgiven by the holder of the debt instrument.

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- Definition

Increase for accrued, but unpaid interest on the debt instrument for the period.

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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

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Amount of debt issuance costs (for example, but not limited to, legal, accounting, broker, and regulatory fees).

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The net amount paid or received by the reporting entity associated with purchase (sale or collection) of loans receivable arising from the financing of goods and services.

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The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

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- Definition

Cash received from principal payments made on loans related to operating activities.

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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

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Loan Payable - Additional Information (Detail) (USD $)	1 Months Ended		3 Months Ended	14 Months Ended
Loan Payable - Additional Information (Detail) (USD $)	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			1,000,000stem_LoanFees
Proceeds received under loan agreement			9,900,000
Initial carrying amount assigned to loan, net of discount			9,512,000stem_CarryingValueOfPurchasedLoans
Fair value allocated to warrant			388,000stem_FairValueAllocatedToWarrant
Note issuance costs			117,000us-gaap_DebtIssuanceCosts
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			$ 1.7034
Warrant expiration period			April 2023
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