The reduction in number of available shares when a share is issued under the share based compensation.

No definition available.

Name:	immr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsReductionInSharesAvailableForGrantForEveryShareIssued
Namespace Prefix:	immr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The estimated dividend rate (a percentage of the share price) used in option-pricing model.

+ References

No definition available.

+ Details

Name:	immr_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendYield
Namespace Prefix:	immr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The highest value of shares that an employee can purchase under the plan per period.

+ References

No definition available.

+ Details

Name:	immr_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumValueOfSharesPerEmployee
Namespace Prefix:	immr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The offering period of the employee stock purchase plan ("ESPP").

+ References

No definition available.

+ Details

Name:	immr_ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriod
Namespace Prefix:	immr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Reserved for Future Issuance

+ References

No definition available.

+ Details

Name:	immr_SharebasedCompensationArrangementbySharebasedPaymentAwardNumberofSharesReservedforFutureIssuance
Namespace Prefix:	immr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares purchased by employees since inception of ESPP.

+ References

No definition available.

+ Details

Name:	immr_SharesPurchasedByEmployeeSinceInceptionOfEmployeeStockPurchasePlan
Namespace Prefix:	immr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Aggregate number of common shares reserved for future issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Unrecognized cost of unvested share-based compensation awards.

+ 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 (i)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, 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)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- 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

- Definition

The highest quantity of shares an employee can purchase under the plan per period.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesPerEmployee
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares purchased on the open market during the period for issuance to employees under the plan.

+ 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
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5047-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesPurchasedForAward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- 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=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- 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

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=immr_StandardStockOptionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=immr_MarketBasedStockOptionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

STOCK-BASED COMPENSATION - Additional Information (Detail) - USD ($)		12 Months Ended
	Jun. 02, 2017	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options for every share issued (in shares)		1.75
Percentage of fair market value on the purchase date		85.00%
Maximum number of shares per employee (in shares)		2,000
Employee stock purchase plan offering period		6 months
Maximum value of shares per employee		$ 25,000
Common stock reserved for issuance (in shares)		1,000,000
Shares purchased by employee since inception of ESPP (in shares)		724,822
Shares purchased under ESPP (in shares)		26,689	48,750
Expected dividend yield in option-pricing model		0.00%
Unrecognized compensation cost		$ 6,000,000
Standard and market condition stock options outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based payment award vesting period (years)		4 years
Shares reserved for issuance (in shares)	3,476,850
Standard and market condition stock options outstanding \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based payment award expiration period (years)		7 years
Standard and market condition stock options outstanding \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based payment award expiration period (years)		10 years
Restricted stock awards outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based payment award vesting period (years)		1 year
Unrecognized compensation cost, recognized over an estimated weighted-average period (years)		5 months 15 days
RSUs outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based payment award vesting period (years)		3 years
Unrecognized compensation cost, recognized over an estimated weighted-average period (years)		1 year 1 month 17 days
Standard stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based payment award vesting period (years)		2 years 5 months 19 days
Market condition based stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based payment award expiration period (years)		7 years