Income Tax (Details) - USD ($)	5 Months Ended	12 Months Ended
Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Income Tax (Details) [Line Items]
Provision for income taxes		$ 38,000	$ 19,000
U.S. NOL carryforwards		7,300,000
Spartacus Acquisition Corp [Member]
Income Tax (Details) [Line Items]
U.S. federal net operating loss	$ 49,757
Change in the valuation allowance	$ 32,373	$ 32,373

Amount of deferred tax assets other tax carryforwards.

No definition available.

Name:	nn_DeferredTaxAssetsOtherTaxCarryforward
Namespace Prefix:	nn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	nn_IncomeTaxDetailsLineItems
Namespace Prefix:	nn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of current foreign income tax expense (benefit) pertaining to income (loss) from continuing operations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(1)(Note 1))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32639-109319

+ Details

Name:	us-gaap_CurrentForeignTaxExpenseBenefit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase (decrease) to previously recorded tax expense. Includes, but is not limited to, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, and IRS tax settlement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 25
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=123452999&loc=d3e28511-109314

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 25
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=123452999&loc=d3e28446-109314

+ Details

Name:	us-gaap_TaxAdjustmentsSettlementsAndUnusualProvisions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of valuation allowance pertaining to the deferred tax asset representing potential future taxable deductions from tax credit carryforwards for which it is more likely than not that a tax benefit will not be realized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32537-109319

+ Details

Name:	us-gaap_TaxCreditCarryforwardValuationAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	srt_ConsolidatedEntitiesAxis=nn_SpartacusAcquisitionCorpMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: