Number Of Debt Instruments

No definition available.

Name:	nptn_NumberOfDebtInstruments
Namespace Prefix:	nptn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- 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

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

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

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 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

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

+ Details

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

- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ 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=118932676&loc=d3e3255-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Definition

Amount of cash outflow for payment of an obligation from a lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

+ 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)(a))
-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 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16)(a)(1))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(13))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Details

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

- Details

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

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
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_DebtInstrumentAxis=nptn_FirstCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nptn_SecondLineofCreditMember
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_ShortTermDebtTypeAxis=us-gaap_ShortTermDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

Debt - Notes Payable (Details)	1 Months Ended						9 Months Ended
Debt - Notes Payable (Details)	Aug. 31, 2018 USD ($)	May 31, 2018 USD ($)	Feb. 28, 2018 USD ($)	Jan. 31, 2018 USD ($)	Nov. 30, 2017 USD ($)	Jul. 31, 2017 USD ($)	Sep. 30, 2019 USD ($) line_of_credit	Sep. 30, 2019 CNY (¥) line_of_credit	Dec. 31, 2018 USD ($)
Debt Instrument [Line Items]
Short-term debt							$ 0		$ 4,795,000
Notes payable to suppliers \| Loans with Suppliers
Debt Instrument [Line Items]
Short-term debt							$ 0		4,795,000
Notes payable to suppliers \| Loans with Suppliers \| Minimum
Debt Instrument [Line Items]
Debt instrument, term							3 months
Notes payable to suppliers \| Loans with Suppliers \| Maximum
Debt Instrument [Line Items]
Debt instrument, term							6 months
Loans Payable \| First Credit Facility
Debt Instrument [Line Items]
Current borrowing capacity							$ 16,800,000	¥ 120,000,000.0
Loans Payable \| Second Line of Credit
Debt Instrument [Line Items]
Current borrowing capacity							4,200,000	30,000,000.0
Bankers Acceptance
Debt Instrument [Line Items]
Restricted cash and investments, current									2,600,000
Bankers Acceptance \| First Credit Facility
Debt Instrument [Line Items]
Current borrowing capacity							$ 33,600,000	240,000,000.0
Percentage of compensating balance requirement for bank acceptance drafts							50.00%
Bankers Acceptance \| Second Line of Credit
Debt Instrument [Line Items]
Percentage of compensating balance requirement for bank acceptance drafts							50.00%
Bankers Acceptance \| Loans with Suppliers
Debt Instrument [Line Items]
Short-term debt							$ 0		$ 4,800,000
Short Term Loans \| Second Line of Credit
Debt Instrument [Line Items]
Current borrowing capacity							$ 8,400,000	¥ 60,000,000.0
Notes Payable to Banks \| Notes Payable CITIC Bank
Debt Instrument [Line Items]
Proceeds from lines of credit			$ 17,000,000.0			$ 17,000,000.0
Debt instrument, interest rate, stated percentage			4.70%
Repayments of lines of credit	$ 17,000,000.0
Debt instrument, basis spread						2.55%
China \| Notes payable to suppliers \| First Credit Facility
Debt Instrument [Line Items]
Proceeds from lines of credit					$ 17,000,000.0
Repayments of lines of credit		$ 17,000,000.0
China \| Bankers Acceptance \| First Credit Facility
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage					4.10%
China \| Notes Payable to Banks \| Notes Payable CITIC Bank
Debt Instrument [Line Items]
Repayments of lines of credit				$ 17,000,000.0
Line of Credit \| China
Debt Instrument [Line Items]
Number of debt instruments \| line_of_credit							2	2
CITIC Bank \| Line of Credit \| China
Debt Instrument [Line Items]
Credit facility, maximum borrowing amount							$ 35,000,000.0	¥ 250,000,000
CITIC Bank \| Bank Acceptance Drafts \| China
Debt Instrument [Line Items]
Percentage of compensating balance requirement for bank acceptance drafts							36.00%
Credit facility, maximum borrowing amount							$ 54,700,000	¥ 390,600,000