XML 41 R30.htm IDEA: XBRL DOCUMENT
v3.21.1

Fair Value - Schedule of Aggregate Fair Value of Marketable Securities (Details) - USD ($) | Mar. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Fair Value Disclosures [Abstract] |  |
Due in one year or less | $ 71,059,000 |
Due after one year through two years | 25,693,000 |
Total marketable securities | $ 96,752,000 | $ 0

X
- Definition Marketable securities maturities after one through two years fair value. + References No definition available. + Details
Name: | tern_MarketableSecuritiesMaturitiesAfterOneThroughTwoYearsFairValue
Namespace Prefix: | tern_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Marketable securities maturities with in one year or less fair value. + References No definition available. + Details
Name: | tern_MarketableSecuritiesMaturitiesWithInOneYearOrLessFairValue
Namespace Prefix: | tern_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_FairValueDisclosuresAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of investment in marketable security. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.4) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details
Name: | us-gaap_MarketableSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant