Debt instrument servicing fee.

No definition available.

Name:	nptn_DebtInstrumentServicingFee
Namespace Prefix:	nptn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt, lump sum payment on the maturity date.

+ References

No definition available.

+ Details

Name:	nptn_DebtLumpSumPaymentOnMaturityDate
Namespace Prefix:	nptn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage of compensating balance requirement for bank acceptance drafts.

+ References

No definition available.

+ Details

Name:	nptn_PercentageOfCompensatingBalanceRequirementForBankAcceptanceDrafts
Namespace Prefix:	nptn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of liabilities incurred by the acquirer as part of consideration transferred in a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 25
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6405-128476

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477

+ Details

Name:	us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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

+ References

+ Details

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

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

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

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num: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

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments applied to principal.

+ References

+ Details

Name:	us-gaap_DebtInstrumentPeriodicPaymentPrincipal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

Amount of debt issuance costs (for example, but not limited to, legal, accounting, broker, and regulatory fees).

+ References

No definition available.

+ Details

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

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20, 22
-Article 5

+ Details

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

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

The carrying value as of the balance sheet date of the current portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Line-of-Credit Arrangement
-URI http://asc.fasb.org/extlink&oid=6517033

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20
-Article 5

+ Details

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

- Definition

The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

+ References

+ Details

Name:	us-gaap_LongTermDebtPercentageBearingVariableInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

No definition available.

+ Details

Name:	us-gaap_RepaymentsOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash outflow for a borrowing supported by a written promise to pay an obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585

+ Details

Name:	us-gaap_RepaymentsOfNotesPayable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The portion of the carrying amount of short-term borrowings outstanding as of the balance sheet date, which accrues interest at a rate subject to change from time to time.

+ References

No definition available.

+ Details

Name:	us-gaap_ShortTermDebtPercentageBearingVariableInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=nptn_ComericaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=nptn_MitsubishiBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=nptn_TunableLaserProductLinesFromEMCORECorporationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=nptn_VariableInterestRatePeriodOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=nptn_VariableInterestRatePeriodTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nptn_FirstCreditFacilityExpiresJuneTwoThousandSixteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=country_CN
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nptn_SecondCreditFacilityExpiresSeptemberTwoThousandFifteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nptn_FirstShortTermFinancingAgreementExpiresAprilTwoThousandFifteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nptn_SecondShortTermFinancingAgreementExpiresMayTwoThousandFifteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nptn_TermLoanBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=nptn_TokyoInterbankOfferRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nptn_SeniorSecuredRevolvingCreditFacilityExpiresNovemberTwoThousandSixteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_FederalFundsEffectiveSwapRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=nptn_DailyAdjustingLondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nptn_TermLoanAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_LoansPayableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_NotesPayableOtherPayablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=nptn_NeoPhotonicsSemiconductorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Additional Information (Details) $ in Thousands, ¥ in Millions					1 Months Ended							3 Months Ended
	Apr. 16, 2015 USD ($)	Feb. 25, 2015 JPY (¥)	Feb. 25, 2015 USD ($)	Jan. 02, 2015 USD ($)	Sep. 30, 2015 CNY (¥)	Jun. 30, 2015 CNY (¥)	May. 31, 2015 USD ($)	Apr. 30, 2015 USD ($)	Feb. 28, 2015 JPY (¥)	Feb. 28, 2015 USD ($)	Jan. 31, 2015 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Mar. 31, 2016 JPY (¥)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 JPY (¥)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Feb. 25, 2015 USD ($)
Debt Instrument [Line Items]
Repayment of notes payable												$ 5,047	$ 5,478
Comerica [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Short-term line of credit facility															$ 23,800		$ 23,800
Mitsubishi Bank [Member]
Debt Instrument [Line Items]
Short-term line of credit facility														¥ 1,400,000,000	$ 12,400	¥ 1,400,000,000	11,800
Tunable Laser Product Lines From EMCORE Corporation [Member]
Debt Instrument [Line Items]
Issuance of notes to the seller of acquired business	$ 15,500			$ 16,000								$ 15,482
Debt Instrument, Term											2 years
Libor Plus Rate [Member] \| Comerica [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate														3.19%	3.19%
First Year [Member] \| Tunable Laser Product Lines From EMCORE Corporation [Member]
Debt Instrument [Line Items]
Note payable, interest rate											5.00%
Second Year [Member] \| Tunable Laser Product Lines From EMCORE Corporation [Member]
Debt Instrument [Line Items]
Note payable, interest rate											13.00%
First Credit Facility Expires June 2016 [Member] \| China
Debt Instrument [Line Items]
Percentage of compensating balance requirement for bank acceptance drafts						30.00%
Second Credit Facility Expires September 2015 [Member] \| China
Debt Instrument [Line Items]
Percentage of compensating balance requirement for bank acceptance drafts					30.00%
First Short-Term Advance Financing Agreement Expires April 2015 [Member]
Debt Instrument [Line Items]
Debt repaid								$ 5,000
Interest rate								4.02%
First Short-Term Advance Financing Agreement Expires April 2015 [Member] \| China
Debt Instrument [Line Items]
Short-term line of credit facility																		$ 5,000
First Short-Term Advance Financing Agreement Expires April 2015 [Member] \| China \| Libor Plus Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate					3.30%
Obligation bear variable interest					3.71%													3.71%
Second Short-Term Advance Financing Agreement Expires May 2015 [Member]
Debt Instrument [Line Items]
Debt repaid							$ 5,000
Interest rate							2.33%
Service fees interest percentage							1.00%
Term Loan B [Member] \| Mitsubishi Bank [Member]
Debt Instrument [Line Items]
Debt, aggregate principal amount		¥ 1,000,000,000																		$ 8,400
Debt, periodic principal payments \| ¥		8,333,000
Debt, lump sum payment on the maturity date \| ¥		8,373,000
Loan structuring fee including consumption tax		¥ 40,500,000	$ 300
Term Loan B [Member] \| Tunable Laser Product Lines From EMCORE Corporation [Member] \| Mitsubishi Bank [Member]
Debt Instrument [Line Items]
Issuance of notes to the seller of acquired business											$ 15,500
Term Loan B [Member] \| Tokyo Interbank Offer Rate [Member] \| Mitsubishi Bank [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.40%	1.40%
Senior Secured Revolving Credit Facility Expires November 2016 [Member] \| Comerica [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity															$ 30,000
Senior Secured Revolving Credit Facility Expires November 2016 [Member] \| Libor Plus Rate [Member] \| Comerica [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate												2.75%
Senior Secured Revolving Credit Facility Expires November 2016 [Member] \| Credit Facility Base Rate [Member] \| Comerica [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate												1.75%
Senior Secured Revolving Credit Facility Expires November 2016 [Member] \| Federal Funds Effective Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate												1.00%
Senior Secured Revolving Credit Facility Expires November 2016 [Member] \| Daily Adjusting LIBOR Rate [member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate												1.00%
Term Loan A [Member] \| Mitsubishi Bank [Member]
Debt Instrument [Line Items]
Debt, aggregate principal amount		¥ 500,000,000																		$ 4,200
Term Loan A [Member] \| Tokyo Interbank Offer Rate [Member] \| Mitsubishi Bank [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.40%	1.40%
Loans Payable \| First Credit Facility Expires June 2016 [Member] \| China
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						¥ 120.0													$ 18,600
Loans Payable \| Second Credit Facility Expires September 2015 [Member] \| China
Debt Instrument [Line Items]
Short-term line of credit facility					¥ 133.0													$ 20,600
Notes Payable \| NeoPhotonics Semiconductor [Member]
Debt Instrument [Line Items]
Repayment of notes payable									¥ 710,000,000	$ 6,000
Bankers Acceptance
Debt Instrument [Line Items]
Restricted cash and investments, current															2,700		2,700
Bankers Acceptance \| China
Debt Instrument [Line Items]
Short-term line of credit facility															$ 8,900		$ 8,900
Bankers Acceptance \| China \| Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Term												3 months
Bankers Acceptance \| China \| Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Term												6 months
Bankers Acceptance \| First Credit Facility Expires June 2016 [Member] \| China
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						¥ 171.4													$ 26,600
Bankers Acceptance \| Second Credit Facility Expires September 2015 [Member] \| China
Debt Instrument [Line Items]
Short-term line of credit facility					¥ 190.0													$ 29,500