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Subsequent Event - Additional Information (Detail) - AbbVie - Subsequent Event $ in Millions | 1 Months Ended
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Oct. 31, 2017 USD ($)
Subsequent Event [Line Items] |
Collaborative arrangement even-based payment amount | $ 30
Collaborative arrangement even-based payment period | 30 days

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- Definition Collaborative arrangement contingent payment amount. + References No definition available. + Details
Name: | nbix_CollaborativeArrangementContingentPaymentAmount
Namespace Prefix: | nbix_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Collaborative Arrangement Even-Based Payment Period + References No definition available. + Details
Name: | nbix_CollaborativeArrangementEvenbasedPaymentPeriod
Namespace Prefix: | nbix_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. + References No definition available. + Details
Name: | us-gaap_SubsequentEventLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=nbix_AbbvieIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |