XML 48 R39.htm IDEA: XBRL DOCUMENT
v3.23.3

Long term debt, net (Details) - USD ($) $ / shares in Units, $ in Thousands |  |  | 9 Months Ended |  |
--- | --- | --- | --- | --- | ---
Jun. 08, 2023 | May 09, 2023 | Sep. 30, 2023 | Sep. 30, 2022 | Jul. 06, 2023 | Dec. 31, 2022
Long term debt, net |  |  |  |  |  |
Warrants |  |  | 44,267,686 |  |  |
Carrying value of the Notes, net of debt issuance cost and discount |  |  | $ 47,067 |  |  |
Amortization of debt issuance costs and discount |  |  | 1,771 |  |  |
Note Purchase Agreement and Indenture Agreement [Member] | Senior Secured Notes due 2026 [Member] |  |  |  |  |  |
Long term debt, net |  |  |  |  |  |
Debt discount of the Notes |  |  | 22,900 |  |  |
Debt Instrument, Aggregate principal amount | $ 20,000 | $ 50,000 |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 10.00% |  |  |  |
Debt Instrument, Maturity Date |  | Dec. 01, 2026 |  |  |  |
Debt Instrument, Frequency of Periodic Payment |  | semi-annually |  |  |  |
Proceeds from issuance of debt | $ 20,000 |  |  |  |  |
Carrying value of the Notes, net of debt issuance cost and discount |  |  | 47,100 |  |  |
Amortization of debt issuance costs and discount |  |  | $ 1,800 |  |  |
Debt Instrument, Redemption Period, Start Date |  |  | May 09, 2024 |  |  |
Debt Instrument, Redemption Price, Percentage |  |  | 101.00% |  |  |
Debt Instrument, Redemption Price, Percentage of Principal Amount at Event of Certain Non-Ordinary Course Asset Sales |  |  | 100.00% |  |  |
Debt Instrument, Redemption Price, Percentage of Principal Amount at Event of Change of Control |  |  | 101.00% |  |  |
Debt Instrument, Covenant Compliance |  |  | the Company was in compliance with all of the applicable debt covenants |  |  |
Note Purchase Agreement and Indenture Agreement [Member] | Senior Secured Notes due 2026 [Member] | Maximum [Member] |  |  |  |  |  |
Long term debt, net |  |  |  |  |  |
Percentage of accrued and unpaid interest on debt |  | 50.00% |  |  |  |
Exercise period of debt issued, from date of initial closing | 30 days |  |  |  |  |
Debt Instrument, Interest Rate, Increase (Decrease) |  |  | 0.50% |  |  |
Debt Instrument, Interest Rate, Increase at Event of Default |  |  | 2.00% |  |  |
Note Purchase Agreement and Indenture Agreement [Member] | Senior Secured Notes due 2026 [Member] | Warrant [Member] |  |  |  |  |  |
Long term debt, net |  |  |  |  |  |
Warrants |  | 18,518,520 |  |  | 7,407,407 |
Exercise price of warrants issued |  | $ 2.16 | $ 2.16 |  | $ 2.16 |
Warrant redemption price per share of underlying common stock |  |  | $ 0.01 |  |  |
Fair value of debt |  | $ 14,600 | $ 22,800 |  | $ 8,200 |
Note Purchase Agreement and Indenture Agreement [Member] | Senior Secured Notes due 2026 [Member] | Warrant [Member] | Minimum [Member] |  |  |  |  |  |
Long term debt, net |  |  |  |  |  |
Debt instrument, Redemption price, Percentage of exercise price of warrants |  |  | 130.00% |  |  |
Note Purchase Agreement and Indenture Agreement [Member] | Senior Secured Notes due 2026 [Member] | Warrant [Member] | Maximum [Member] |  |  |  |  |  |
Long term debt, net |  |  |  |  |  |
Exercise period of debt issued, from date of initial closing |  |  | 3535 days |  |  |

X
- Definition The incremental percentage increase (decrease) in the stated rate on a debt instrument at the event of default. + References No definition available. + Details
Name: | nn_DebtInstrumentInterestRateIncreaseAtEventOfDefault
Namespace Prefix: | nn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The percentage price of exercise amount of warrants at which debt can be redeemed by the issuer. + References No definition available. + Details
Name: | nn_DebtInstrumentRedemptionPricePercentageOfExercisePriceOfWarrants
Namespace Prefix: | nn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The percentage price of original principal amount of debt at which debt can be redeemed by the issuer at the event of certain non-ordinary course asset sales, including sales of certain intellectual property or spectrum licensed by the FCC to the reporting entity or its subsidiaries. + References No definition available. + Details
Name: | nn_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountAtEventOfCertainNonOrdinaryCourseAssetSales
Namespace Prefix: | nn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The percentage price of original principal amount of debt at which debt can be redeemed by the issuer at the event of a change of control. + References No definition available. + Details
Name: | nn_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountAtEventOfChangeOfControl
Namespace Prefix: | nn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The period of exercise of debt from the date of initial closing of debt issued. + References No definition available. + Details
Name: | nn_ExercisePeriodOfDebtIssuedFromDateOfInitialClosing
Namespace Prefix: | nn_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The percentage of accrued and unpaid interest on debt issued. + References No definition available. + Details
Name: | nn_PercentageOfAccruedAndUnpaidInterestOnDebt
Namespace Prefix: | nn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of amortization expense attributable to debt discount (premium) and debt issuance costs. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 69E -Publisher FASB -URI https://asc.fasb.org//1943274/2147481568/470-20-55-69E Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 69F -Publisher FASB -URI https://asc.fasb.org//1943274/2147481568/470-20-55-69F Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1F -Subparagraph (b)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-28 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482925/835-30-45-3 + Details
Name: | us-gaap_AmortizationOfFinancingCostsAndDiscounts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Exercise price per share or per unit of warrants or rights outstanding. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481112/505-10-50-3 + Details
Name: | us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of warrants or rights outstanding. + References No definition available. + Details
Name: | us-gaap_ClassOfWarrantOrRightOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition States whether the entity was in compliance with the debt covenants throughout the reporting period, and describes facts and circumstances of any compliance failure. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -SubTopic 10 -Topic 210 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (g) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480848/942-470-50-3 + Details
Name: | us-gaap_DebtInstrumentCovenantCompliance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482900/835-30-50-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 69B -Publisher FASB -URI https://asc.fasb.org//1943274/2147481568/470-20-55-69B Reference 4: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 69C -Publisher FASB -URI https://asc.fasb.org//1943274/2147481568/470-20-55-69C Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482925/835-30-45-2 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482949/835-30-55-8 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Description of the frequency of periodic payments (monthly, quarterly, annual). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480848/942-470-50-3 + Details
Name: | us-gaap_DebtInstrumentFrequencyOfPeriodicPayment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Incremental percentage increase (decrease) in the stated rate on a debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentInterestRateIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types: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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482900/835-30-50-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(f)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04(a)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480678/235-10-S99-3 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 5: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 69B -Publisher FASB -URI https://asc.fasb.org//1943274/2147481568/470-20-55-69B Reference 6: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 69C -Publisher FASB -URI https://asc.fasb.org//1943274/2147481568/470-20-55-69C Reference 7: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 69E -Publisher FASB -URI https://asc.fasb.org//1943274/2147481568/470-20-55-69E Reference 8: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 69F -Publisher FASB -URI https://asc.fasb.org//1943274/2147481568/470-20-55-69F Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 11: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 13: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 14: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (h) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 15: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1D -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1D Reference 16: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1D -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1D Reference 17: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1D -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1D Reference 18: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1E -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1E Reference 19: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1E -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1E Reference 20: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1E -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1E Reference 21: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1F -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F Reference 22: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1F -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F Reference 23: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1F -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F Reference 24: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1F -Subparagraph (b)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1F Reference 25: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1I -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I + Details
Name: | us-gaap_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(2)) -SubTopic 10 -Topic 210 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_DebtInstrumentMaturityDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Start date of debt instrument redemption period, in YYYY-MM-DD format. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph e -SubTopic 470 -Topic 942 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480848/942-470-50-3 + Details
Name: | us-gaap_DebtInstrumentRedemptionPeriodStartDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage price of original principal amount of debt at which debt can be redeemed by the issuer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph e -SubTopic 470 -Topic 942 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480848/942-470-50-3 + Details
Name: | us-gaap_DebtInstrumentRedemptionPricePercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of debt discount to be amortized after one year or the normal operating cycle, if longer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 1A -Publisher FASB -URI https://asc.fasb.org//1943274/2147482925/835-30-45-1A Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482949/835-30-55-8 + Details
Name: | us-gaap_DebtInstrumentUnamortizedDiscountNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Par value per share of mandatory redeemable financial instrument classified as liability. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 4 -SubTopic 10 -Topic 480 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481648/480-10-50-4 + Details
Name: | us-gaap_FinancialInstrumentSubjectToMandatoryRedemptionParValuePerShare
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. + References No definition available. + Details
Name: | us-gaap_LongTermDebtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt classified as noncurrent. Excludes lease obligation. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_LongTermDebtNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 14 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-14 + Details
Name: | us-gaap_ProceedsFromIssuanceOfDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | nn_AgreementTypeAxis=nn_NotePurchaseAgreementAndIndentureAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_SecuredDebtMember
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_StatementEquityComponentsAxis=us-gaap_WarrantMember
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: |