XML 178 R158.htm IDEA: XBRL DOCUMENT
v3.21.1

STOCK-BASED COMPENSATION (Details) - 2009 Stock Plan - shares | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Mar. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Shares reserved for issuance under the plan |  | 55,305,506 | 55,305,506
Exercise price as a percentage of fair value |  | 100.00% |
Exercise price as a percentage of fair value for shareholders owning specified minimum amount |  | 110.00% |
Significant shareholder threshold used for determining exercise price |  | 10.00% |
Number of years for monthly vesting |  | 3 years |
Exercise period | 10 years | 10 years |

X
- Definition The period of time over which a monthly vesting schedule is used. + References No definition available. + Details
Name: | stem_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingNumberOfYearsOfMonthlyVesting
Namespace Prefix: | stem_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The exercise price for a share based compensation award as a percent of fair value to be used as a minimum for shareholders owning a specified amount of shares outstanding. + References No definition available. + Details
Name: | stem_ShareBasedCompensationArrangementPurchasePriceForSignificantShareholders
Namespace Prefix: | stem_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The ownership threshold used to determine if a recipient of a share based compensation award uses a different percentage of fair value for exercise price of awards. + References No definition available. + Details
Name: | stem_SignificantShareholderThresholdPercentageOwnership
Namespace Prefix: | stem_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of shares authorized for issuance under share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Purchase price of common stock expressed as a percentage of its fair value. + References No definition available. + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_PlanNameAxis=stem_StockPlan2009Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |