XML 19 R27.htm IDEA: XBRL DOCUMENT
v3.19.3

Investments - Summary of Investments Classified as AFS Debt Securities (Detail) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2019 | Dec. 31, 2018
Commercial paper |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Aggregate Estimated Fair Value | $ 135,197 | $ 94,572
Corporate debt securities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Aggregate Estimated Fair Value | 414,951 | 544,978
Securities of government-sponsored entities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Aggregate Estimated Fair Value | 158,170 | 85,677
Short-term investments |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Amortized Cost | 502,660 | 510,889
Gross Unrealized Gains | 894 | 8
Gross Unrealized Losses | (29) | (1,698)
Aggregate Estimated Fair Value | 503,525 | 509,199
Short-term investments | Commercial paper |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Amortized Cost | 135,156 | 94,617
Gross Unrealized Gains | 45 |
Gross Unrealized Losses | (4) | (45)
Aggregate Estimated Fair Value | $ 135,197 | $ 94,572
Short-term investments | Commercial paper | Maximum |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available for sale securities contractual maturity | 1 year | 1 year
Short-term investments | Corporate debt securities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Amortized Cost | $ 254,811 | $ 395,385
Gross Unrealized Gains | 577 |
Gross Unrealized Losses | (21) | (1,598)
Aggregate Estimated Fair Value | $ 255,367 | $ 393,787
Short-term investments | Corporate debt securities | Maximum |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available for sale securities contractual maturity | 1 year | 1 year
Short-term investments | Securities of government-sponsored entities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Amortized Cost | $ 112,693 | $ 20,887
Gross Unrealized Gains | 272 | 8
Gross Unrealized Losses | (4) | (55)
Aggregate Estimated Fair Value | $ 112,961 | $ 20,840
Short-term investments | Securities of government-sponsored entities | Maximum |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available for sale securities contractual maturity | 1 year | 1 year
Long-term investments |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Amortized Cost | $ 204,052 | $ 216,270
Gross Unrealized Gains | 794 | 228
Gross Unrealized Losses | (53) | (470)
Aggregate Estimated Fair Value | 204,793 | 216,028
Long-term investments | Corporate debt securities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Amortized Cost | 159,035 | 151,594
Gross Unrealized Gains | 602 | 66
Gross Unrealized Losses | (53) | (469)
Aggregate Estimated Fair Value | $ 159,584 | $ 151,191
Long-term investments | Corporate debt securities | Minimum |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available for sale securities contractual maturity | 1 year | 1 year
Long-term investments | Corporate debt securities | Maximum |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available for sale securities contractual maturity | 2 years | 2 years
Long-term investments | Securities of government-sponsored entities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Amortized Cost | $ 45,017 | $ 64,676
Gross Unrealized Gains | 192 | 162
Gross Unrealized Losses |  | (1)
Aggregate Estimated Fair Value | $ 45,209 | $ 64,837
Long-term investments | Securities of government-sponsored entities | Minimum |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available for sale securities contractual maturity | 1 year | 1 year
Long-term investments | Securities of government-sponsored entities | Maximum |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available for sale securities contractual maturity | 2 years | 2 years

X
- Definition The term of contractual maturity for available for sale debt securities, in PnY format. + References No definition available. + Details
Name: | nbix_AvailableForSaleDebtSecuritiesContractualMaturity
Namespace Prefix: | nbix_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454 + Details
Name: | us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_CashAndCashEquivalentsAxis=us-gaap_CommercialPaperMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=nbix_SecuritiesOfGovernmentSponsoredEntitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=nbix_LongTermInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |