XML 39 R29.htm IDEA: XBRL DOCUMENT
v3.21.2

Debt Securities - Additional Information (Detail) $ in Millions | 6 Months Ended |
--- | --- | ---
Jun. 30, 2021 USD ($) security | Jun. 30, 2020 USD ($) | Dec. 31, 2020 USD ($)
Investments, Debt and Equity Securities [Abstract] |  |  |
Number of debt securities available for sale | security | 142 |  |
Number of debt securities available for sale in unrealized loss position | security | 56 |  |
Accrued interest receivables | $ | $ 2.7 |  | $ 3.7
Accrued interest receivables write-off | $ | $ 0.0 | $ 0.0 |

X
- Definition Debt securities available for sale position number of positions. + References No definition available. + Details
Name: | nbix_DebtSecuritiesAvailableForSalePositionNumberOfPositions
Namespace Prefix: | nbix_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of writeoff of accrued interest on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), recognized by reversing interest income. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 3D -URI http://asc.fasb.org/extlink&oid=124269663&loc=SL120267862-210455 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleAccruedInterestWriteoff
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27290-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922888-210455 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Carrying amount as of the balance sheet date of current interest earned but not received. Also called accrued interest or accrued interest receivable. For classified balance sheets, represents the current amount receivable, that is amounts expected to be collected within one year or the normal operating cycle, if longer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.8) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_InterestReceivableCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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