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BIAL Agreement - Additional Information (Detail) - B I A L - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Mar. 31, 2017 | Sep. 30, 2017
License Agreement [Line Items] |  |
License agreement date |  | Feb. 09, 2017
Up-front license fees | $ (30) |
Milestone payables | $ 115 |

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- Definition Up front payments received (paid) under collaborative agreements for sponsored research and development, and licensing fees + References No definition available. + Details
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Balance Type: | credit
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- Definition Date of the license agreement, in CCYY-MM-DD format. + References No definition available. + Details
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Balance Type: | na
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose the terms and amounts of a license agreement. + References No definition available. + Details
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Data Type: | xbrli:stringItemType
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- Definition The amount of potential milestone payments to be paid under a license agreement. + References No definition available. + Details
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Namespace Prefix: | nbix_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Details
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Namespace Prefix: |
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