Amount of annual base rent.

No definition available.

Name:	imsr_LesseeOperatingLeaseAnnualBaseRent
Namespace Prefix:	imsr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percentage of annual incremental rate for the annual base rent.

+ References

No definition available.

+ Details

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Namespace Prefix:	imsr_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Area of office space taken on lease.

+ References

No definition available.

+ Details

Name:	imsr_LesseeOperatingLeaseAreaOfOfficeSpace
Namespace Prefix:	imsr_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of renewal options available for lessee.

+ References

No definition available.

+ Details

Name:	imsr_LesseeOperatingLeaseNumberOfRenewalOptions
Namespace Prefix:	imsr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents number of lease arrangements.

+ References

No definition available.

+ Details

Name:	imsr_NumberOfLeaseArrangements
Namespace Prefix:	imsr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Area of land held.

+ References

No definition available.

+ Details

Name:	us-gaap_AreaOfLand
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-7A

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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Indicates (true false) whether lessee has option to extend operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_LesseeOperatingLeaseTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Present value of lessee's discounted obligation for lease payments from operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-1

+ Details

Name:	us-gaap_OperatingLeaseLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Present value of lessee's discounted obligation for lease payments from operating lease, classified as current.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Present value of lessee's discounted obligation for lease payments from operating lease, classified as noncurrent.

+ References

+ Details

Name:	us-gaap_OperatingLeaseLiabilityNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of lessee's right to use underlying asset under operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-1

+ Details

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

- Definition

Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 53
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479589/842-20-55-53

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-4

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=imsr_TexasAandMRellisCampusOfficeSpaceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=imsr_TexasAandMRellisCampusGroundLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LeaseContractualTermAxis=imsr_LeaseExpiringOnMarch312028Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LeaseContractualTermAxis=imsr_LeaseExpiringOnSeptember12026Member
Namespace Prefix:
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Balance Type:
Period Type:

Leases (Details) $ in Thousands		1 Months Ended	6 Months Ended
Leases (Details) $ in Thousands	Jun. 15, 2026 USD ($) a lease	Mar. 31, 2026 USD ($) ft² item	Jun. 30, 2026 USD ($) lease	Dec. 31, 2025 USD ($)
Leases
Number Of Lease Arrangements \| lease			3
Right of use asset and corresponding lease liability			$ 2,125
Operating lease right-of-use assets			3,595	$ 1,814
Operating lease liabilities			3,809	1,984
Operating lease liabilities, current			1,803	383
Operating lease liabilities, noncurrent			$ 2,006	$ 1,601
Office space
Leases
Area of office space \| ft²		1,775
Term of contract		2 years
Number of renewal options \| item		3
Renewal term		1 year
Option to extend		true
Annual base rent		$ 116
Incremental rate on annual base rent		3.50%
Ground lease
Leases
Number Of Lease Arrangements \| lease	2
Area of Land \| a	77.7
Ground lease \| Lease expiring on March 31, 2028
Leases
Annual base rent	$ 1,110
Incremental rate on annual base rent	3.75%
Area of Land \| a	44.4
Ground lease \| Lease expiring on September 1, 2026
Leases
Annual base rent	$ 800
Area of Land \| a	33.3