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v3.21.1

Organization and Significant Accounting Policies - Additional Information (Detail) | 3 Months Ended
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Mar. 31, 2021 subsidiary
Accounting Policies [Abstract] |
Number of wholly owned Irish subsidiaries | 2

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- Definition Number Of Irish Subsidiaries + References No definition available. + Details
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Namespace Prefix: | nbix_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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