Fair Value Measurements - Summary of Financial Assets Recognized at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Marketable securities:
Investment in Kyverna Therapeutics, Inc.	$ 29,158	$ 10,000
Fair Value on Recurring Basis [Member]
Assets
Cash equivalents and restricted cash equivalents	143,500	136,254
Marketable securities:
Marketable securities	781,405	785,339
Investment in Kyverna Therapeutics, Inc.	29,158
Total Assets	954,063	921,593
Fair Value on Recurring Basis [Member] \| U.S. Treasury and Other Government - Backed Securities [Member]
Marketable securities:
Marketable securities	401,111	382,308
Fair Value on Recurring Basis [Member] \| Financial Institution Debt Securities [Member]
Marketable securities:
Marketable securities	213,765	246,119
Fair Value on Recurring Basis [Member] \| Corporate Debt Securities [Member]
Marketable securities:
Marketable securities	112,077	97,408
Fair Value on Recurring Basis [Member] \| Other Asset Backed Securities [Member]
Marketable securities:
Marketable securities	54,452	59,504
Fair Value on Recurring Basis [Member] \| Level 1 [Member]
Assets
Cash equivalents and restricted cash equivalents	143,500	136,254
Marketable securities:
Marketable securities	179,434	120,556
Investment in Kyverna Therapeutics, Inc.	29,158
Total Assets	352,092	256,810
Fair Value on Recurring Basis [Member] \| Level 1 [Member] \| U.S. Treasury and Other Government - Backed Securities [Member]
Marketable securities:
Marketable securities	179,434	120,556
Fair Value on Recurring Basis [Member] \| Level 2 [Member]
Marketable securities:
Marketable securities	601,971	664,783
Total Assets	601,971	664,783
Fair Value on Recurring Basis [Member] \| Level 2 [Member] \| U.S. Treasury and Other Government - Backed Securities [Member]
Marketable securities:
Marketable securities	221,677	261,752
Fair Value on Recurring Basis [Member] \| Level 2 [Member] \| Financial Institution Debt Securities [Member]
Marketable securities:
Marketable securities	213,765	246,119
Fair Value on Recurring Basis [Member] \| Level 2 [Member] \| Corporate Debt Securities [Member]
Marketable securities:
Marketable securities	112,077	97,408
Fair Value on Recurring Basis [Member] \| Level 2 [Member] \| Other Asset Backed Securities [Member]
Marketable securities:
Marketable securities	$ 54,452	$ 59,504

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

+ Details

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

- Definition

Fair value portion of investments in an entity not consolidated. Includes, but is not limited to, investments in an entity that is affiliated with the reporting entity by means of direct or indirect ownership, an entity in which the reporting entity shares control of the entity with another party or group, an entity which the company has significant influence, but does not have control and subsidiaries that are not required to be consolidated and are accounted for using the equity or cost method.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

+ Details

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

- References

No definition available.

+ Details

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

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=ntla_USTreasuryAndOtherGovernmentBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=ntla_FinancialInstitutionDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: