Restructuring - Summary of Restructuring Activity (Details) $ in Millions	9 Months Ended
Sep. 30, 2026 USD ($)
Phase I of the Indivior Action Agenda
Restructuring Reserve [Roll Forward]
Beginning balance	$ 54
Restructuring charges	16
Cash payments	(38)
Non-cash charges	(8)
Ending balance	23
Phase I of the Indivior Action Agenda \| Contract termination and related expenses, and impairment of long-lived assets
Restructuring Reserve [Roll Forward]
Beginning balance	18
Restructuring charges	8
Cash payments	(8)
Non-cash charges	(8)
Ending balance	10
Phase I of the Indivior Action Agenda \| Severance, legal, consulting, and other corporate initiative transition costs
Restructuring Reserve [Roll Forward]
Beginning balance	36
Restructuring charges	8
Cash payments	(31)
Non-cash charges	0
Ending balance	13
Cease Phase 3 Development of INDV-6001 and not Advance INDV-2000 Internally
Restructuring Reserve [Roll Forward]
Beginning balance	0
Restructuring charges	6
Cash payments	(1)
Non-cash charges	0
Ending balance	$ 5

Restructuring Reserve, Adjustment for Non-Cash Expense

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- Definition

Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 17
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 420
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482017/420-10-50-1

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- Definition

Carrying amount as of the balance sheet date of known and estimated obligations associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, which are expected to be paid in the next twelve months or in the normal operating cycle if longer. Costs of such activities include those for one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, relocating employees, and costs associated with an ongoing benefit arrangement, but excludes costs associated with the retirement of a long-lived asset.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 420
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482017/420-10-50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 420
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 5.P.4.b.2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479823/420-10-S99-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(20))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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- Definition

Amount of restructuring charges, remediation cost, and asset impairment loss.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(3))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2

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