Debt Instrument, Interest Rate, Loan Fee

No definition available.

Name:	nptn_DebtInstrumentInterestRateLoanFee
Namespace Prefix:	nptn_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of a specific compensating balance arrangement that is maintained under an agreement for a bank loan or future credit availability.

+ 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 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_CompensatingBalanceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

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=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- 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

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Balance Type:	na
Period Type:	duration

- 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

- Definition

Fair value of the amount outstanding under the credit facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ 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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Details

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- Details

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- Details

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- Details

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- Details

Name:	srt_ConsolidatedEntitiesAxis=srt_SubsidiariesMember
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- Details

Name:	us-gaap_DebtInstrumentAxis=nptn_CreditLineAgreementMember
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- Details

Name:	dei_LegalEntityAxis=nptn_NeoPhotonicsChinaCoLtdMember
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- Details

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- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_BankersAcceptanceMember
Namespace Prefix:
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Balance Type:
Period Type:

Debt - Notes Payable and Short-term Borrowing (Details)	9 Months Ended
Debt - Notes Payable and Short-term Borrowing (Details)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 CNY (¥)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Notes payable \| China \| Minimum
Debt Instrument [Line Items]
Debt term	3 months
Notes payable \| China \| Maximum
Debt Instrument [Line Items]
Debt term	6 months
Notes payable \| China \| Subsidiaries \| Credit Line Agreement \| NeoPhotonics China
Debt Instrument [Line Items]
Credit facility, maximum borrowing amount		¥ 120,000,000	$ 18,600,000
Outstanding balance of line of credit facilities	$ 15,000,000			$ 0
Interest rate	3.00%
Loan fees	2.40%
Notes payable \| China \| Subsidiaries \| Credit Line Agreement \| NeoPhotonics Donggua
Debt Instrument [Line Items]
Credit facility, maximum borrowing amount		¥ 30,000,000	$ 4,600,000
Outstanding balance of line of credit facilities	$ 0
Bankers acceptance
Debt Instrument [Line Items]
Compensating balances	$ 0			$ 0