XML 54 R37.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Convertible Senior Notes - Additional Information (Detail) $ / shares in Units, shares in Millions |  | 12 Months Ended
--- | --- | ---
May 02, 2017 USD ($) | Dec. 31, 2018 USD ($) d $ / shares shares | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($)
Debt Instrument [Line Items] |  |  |  |
Convertible senior notes principal amount |  | $ 517,500,000 | $ 517,500,000 |
Proceeds from Senior Convertible Notes |  | $ 0 | $ 502,781,000 | $ 0
2.25% Convertible Senior Notes due 2024 |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Convertible senior notes principal amount | $ 517,500,000 |  |  |
Convertible senior notes interest percentage | 2.25% |  |  |
Convertible senior notes interest rate | 2.25% |  |  |
Convertible senior notes convertible latest date |  | May 15, 2024 |  |
Proceeds from Senior Convertible Notes | $ 502,800,000 |  |  |
Threshold common stock trading days | d |  | 20 |  |
Threshold consecutive common stock trading days | d |  | 30 |  |
Threshold percentage of common stock price trigger |  | 130.00% |  |
Debt instrument conversion obligation number of consecutive business days after consecutive trading day period |  | 5 days |  |
Debt instrument conversion obligation period of consecutive trading days. |  | 5 days |  |
Principal amount on conversion rate |  | $ 1,000 |  |
Minimum percentage of common stock price trigger |  | 98.00% |  |
Debt instrument convertible trading days during observation period |  | 30 days |  |
Conversion Observation Period |  | 25 days |  |
Debt instrument conversion value description |  | The conversion value is the sum of the daily conversion value which is the product of the effective conversion rate divided by 25 days and the daily VWAP of the Company’s common stock. |  |
Debt instrument conversion share amount description |  | The “share amount” is the cumulative “daily share amount” during the observation period, which is calculated by dividing the daily VWAP into the difference between the daily conversion value (i.e., conversion rate x daily VWAP) and $1,000. |  |
Convertible senior notes convertible in to shares |  | 0.00131711 |  |
Convertible senior notes conversion price | $ / shares |  | $ 75.92 |  |
Shares issued to settle notes at initial conversion rate | shares |  | 6.8 |  |
Market Price of Common stock | $ / shares |  | $ 53.28 |  |
Convertible senior note premium |  | 42.50% |  |
Convertible senior notes redemption rate |  | 100.00% |  |
Fair value of convertible senior note as percentage of principal amount |  | 119.00% | 128.00% |
Convertible senior note carrying value of the liability component |  | $ 368,300,000 |  |
Convertible senior note assumed borrowing rate |  | 7.50% |  |
Convertible senior note carrying value of the equity component |  | $ 149,200,000 |  |
Convertible senior notes |  | 7 years |  |
Transaction cost related to issuance of convertible senior note |  | $ 14,700,000 |  |
Debt instrument events of default percentage of principal and accrued and unpaid interest due and payable upon default |  | 100.00% |  |

X
- Definition The duration of time during which the weighted-average share price is used to calculate the excess conversion value due upon conversion of a convertible note, in the format of PnYnMnD. + References No definition available. + Details
Name: | nbix_DebtConversionObservationPeriod
Namespace Prefix: | nbix_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Debt instrument conversion obligation number of consecutive business days after consecutive trading day period. + References No definition available. + Details
Name: | nbix_DebtInstrumentConversionObligationNumberOfConsecutiveBusinessDaysAfterConsecutiveTradingDayPeriod
Namespace Prefix: | nbix_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Debt instrument conversion obligation period of consecutive trading days. + References No definition available. + Details
Name: | nbix_DebtInstrumentConversionObligationPeriodOfConsecutiveTradingDays
Namespace Prefix: | nbix_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Debt instrument conversion share amount description. + References No definition available. + Details
Name: | nbix_DebtInstrumentConversionShareAmountDescription
Namespace Prefix: | nbix_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Debt instrument conversion value description. + References No definition available. + Details
Name: | nbix_DebtInstrumentConversionValueDescription
Namespace Prefix: | nbix_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The percentage of excess of the price paid for the convertible note over the closing stock price on the closing date of the convertible note. + References No definition available. + Details
Name: | nbix_DebtInstrumentConvertibleConversionPremium
Namespace Prefix: | nbix_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The carrying amount of the liability component of a convertible note. + References No definition available. + Details
Name: | nbix_DebtInstrumentConvertibleInitialCarryingAmountOfLiabilityComponent
Namespace Prefix: | nbix_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Debt instrument convertible trading days during observation period. + References No definition available. + Details
Name: | nbix_DebtInstrumentConvertibleTradingDaysDuringObservationPeriod
Namespace Prefix: | nbix_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Debt instrument events of default percentage of principal and accrued and unpaid interest due and payable upon default. + References No definition available. + Details
Name: | nbix_DebtInstrumentEventsOfDefaultPercentageOfPrincipalAndAccruedAndUnpaidInterestDueAndPayableUponDefault
Namespace Prefix: | nbix_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Debt instrument fair value percentage of principal. + References No definition available. + Details
Name: | nbix_DebtInstrumentFairValuePercentageOfPrincipal
Namespace Prefix: | nbix_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The minimum percentage of the product of the common stock trading price multiplied by the conversion rate during the measurement period as compared to the principal note amount that triggers a conversion option on the notes, if it falls below this percentage. + References No definition available. + Details
Name: | nbix_MinimumPercentageOfTradingPriceToLastReportedSalePrice
Namespace Prefix: | nbix_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Principal amount on conversion rate. + References No definition available. + Details
Name: | nbix_PrincipalAmountOnConversionRate
Namespace Prefix: | nbix_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The number of shares issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or payments in the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586 + Details
Name: | us-gaap_DebtConversionConvertedInstrumentSharesIssued1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The rate of interest that was being paid on the original debt issue that is being converted in the noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586 + Details
Name: | us-gaap_DebtConversionOriginalDebtInterestRateOfDebt
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870 + Details
Name: | us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The price per share of the conversion feature embedded in the debt instrument. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031898-161870 + Details
Name: | us-gaap_DebtInstrumentConvertibleConversionPrice1
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(5)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644 + Details
Name: | us-gaap_DebtInstrumentConvertibleConversionRatio1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Latest date when the debt instrument can be converted into equity, in CCYY-MM-DD format. + 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 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644 + Details
Name: | us-gaap_DebtInstrumentConvertibleLatestDate1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Threshold period of specified consecutive trading days within which common stock price to conversion price of convertible debt instrument must exceed threshold percentage for specified number of trading days to trigger conversion feature. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Minimum percentage of common stock price to conversion price of convertible debt instruments to determine eligibility of conversion. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Threshold number of specified trading days that common stock price to conversion price of convertible debt instruments must exceed threshold percentage within a specified consecutive trading period to trigger conversion feature. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentConvertibleThresholdTradingDays
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The average effective interest rate during the reporting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateDuringPeriod
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + 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 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
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_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of principal amount of debt redeemed. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399 + Details
Name: | us-gaap_DeferredFinanceCostsGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The cash inflow from the issuance of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromConvertibleDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Price of a single share of a number of saleable stocks of a company. + References No definition available. + Details
Name: | us-gaap_SharePrice
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_DebtInstrumentAxis=nbix_SeniorConvertibleNotesTwoPointTwoFivePercentDueInMayTwoThousandTwentyFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |