Aggregate pre specified development milestones for second indication product.

No definition available.

Name:	tern_AggregatePreSpecifiedDevelopmentMilestonesForSecondIndicationProduct
Namespace Prefix:	tern_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Aggregate pre specified development milestones product ex mainland.

+ References

No definition available.

+ Details

Name:	tern_AggregatePreSpecifiedDevelopmentMilestonesProductExMainland
Namespace Prefix:	tern_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Aggregate pre specified development milestones product mainland.

+ References

No definition available.

+ Details

Name:	tern_AggregatePreSpecifiedDevelopmentMilestonesProductMainland
Namespace Prefix:	tern_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Agreement milestones payment.

+ References

No definition available.

+ Details

Name:	tern_AgreementMilestonesPayment
Namespace Prefix:	tern_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Assignment license and collaboration agreements.

+ References

No definition available.

+ Details

Name:	tern_AssignmentLicenseAndCollaborationAgreementsLineItems
Namespace Prefix:	tern_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Milestone payment.

+ References

No definition available.

+ Details

Name:	tern_MilestonePayment
Namespace Prefix:	tern_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of days advance written notice.

+ References

No definition available.

+ Details

Name:	tern_NumberOfDaysAdvanceWrittenNotice
Namespace Prefix:	tern_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Option and license agreement pre specified clinical regulatory sales milestones.

+ References

No definition available.

+ Details

Name:	tern_OptionAndLicenseAgreementPreSpecifiedClinicalRegulatorySalesMilestones
Namespace Prefix:	tern_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Upfront payment.

+ References

No definition available.

+ Details

Name:	tern_UpfrontPayment
Namespace Prefix:	tern_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Upfront payment received.

+ References

No definition available.

+ Details

Name:	tern_UpfrontPaymentReceived
Namespace Prefix:	tern_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Upfront payment research and development expense.

+ References

No definition available.

+ Details

Name:	tern_UpfrontPaymentResearchAndDevelopmentExpense
Namespace Prefix:	tern_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 912
-SubTopic 730
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6472174&loc=d3e58812-109433

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373

+ Details

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

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9038-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130543-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis=tern_TERNOneHundredAndOneLicenseAgreementWithEliLillyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=country_CN
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis=tern_TERNTwoHundredAndOneLicenseAgreementWithEliLillyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_ResearchAndDevelopmentExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis=tern_AssignmentAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis=tern_HansohOptionAndLicenseAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

Assignment, License and Collaboration Agreements - Additional Information (Details)	1 Months Ended					12 Months Ended
	Nov. 30, 2021 USD ($)	Jul. 31, 2020 USD ($)	Jun. 30, 2019 CNY (¥)	Mar. 31, 2018 USD ($)	Feb. 28, 2018 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Assignment License And Collaboration Agreements [Line Items]
License revenue						$ 1,000,000	$ 0
TERN-101 License Agreement with Eli Lilly
Assignment License And Collaboration Agreements [Line Items]
Agreement milestones payment						0
Research and development expense						0	0
TERN-101 License Agreement with Eli Lilly \| China
Assignment License And Collaboration Agreements [Line Items]
Aggregate pre-specified development milestones for the first covered product					$ 6,000,000.0
Aggregate pre-specified development milestones for the first covered product in ex-mainland					$ 50,000,000.0
TERN-201 License Agreement with Eli Lilly
Assignment License And Collaboration Agreements [Line Items]
Aggregate pre-specified development milestones for the first covered product				$ 74,000,000.0
Agreement milestones payment						0
Research and development expense						0	0
Aggregate pre-specified development milestones for second indication of covered product				$ 30,000,000.0
Amount paid under the agreement						4,000,000.0
TERN-201 License Agreement with Eli Lilly \| Research and Development Expense
Assignment License And Collaboration Agreements [Line Items]
Upfront payment									$ 4,000,000.0
Assignment Agreement
Assignment License And Collaboration Agreements [Line Items]
Aggregate pre-specified development milestones for the first covered product \| ¥			¥ 205,000,000.0
Research and development expense						0	1,500,000
Amount paid under the agreement						$ 2,200,000
Number of days advance written notice						60 days
Milestone payment						$ 1,500,000
Assignment Agreement \| Research and Development Expense
Assignment License And Collaboration Agreements [Line Items]
Upfront payment								$ 700,000
Hansoh Option and License Agreement
Assignment License And Collaboration Agreements [Line Items]
Upfront payment received							$ 800,000
License revenue	$ 1,000,000.0
Hansoh Option and License Agreement \| Maximum
Assignment License And Collaboration Agreements [Line Items]
Amount agree to pay in pre-specified clinical, regulatory and sales milestones		$ 67,000,000.0