Commitments and contingencies (Details) ¥ in Thousands					1 Months Ended												3 Months Ended		6 Months Ended		12 Months Ended
	Oct. 25, 2017 CNY (¥)	Oct. 25, 2017 USD ($)	Jun. 16, 2017 USD ($)	Dec. 27, 2016 USD ($)	Jun. 30, 2019 USD ($)	Feb. 28, 2019 CNY (¥)	Feb. 28, 2019 USD ($)	Jan. 31, 2019 USD ($)	Dec. 31, 2018 CNY (¥) lawsuit	Dec. 31, 2018 USD ($) lawsuit	Nov. 30, 2018 CNY (¥)	Nov. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jul. 31, 2018 USD ($)	Apr. 30, 2018 USD ($)	Nov. 30, 2016 lawsuit	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2010 lawsuit claim	Apr. 30, 2019 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2012 USD ($)
Commitments And Contingencies Disclosure [Line Items]
Number of defendants | lawsuit																							4
Penalty payment derivative										$ 2,000,000
Gain on asset sale																	$ 817,000	$ 0	$ 817,000	$ 0		$ 2,200,000
NeoPhotonics Corporation, LLC | Disposed of by Sale
Commitments And Contingencies Disclosure [Line Items]
Consideration received pursuant to asset purchase agreement																								$ 2,000,000
Percent of ownership disposed																								100.00%
Exit fee settlements																								$ 2,000,000
Gain on asset sale																	$ 800,000		800,000
Russian federation | Scenario, Forecast
Commitments And Contingencies Disclosure [Line Items]
Exit fees for future																					$ 2,000,000
Embedded derivative financial instruments | Maximum
Commitments And Contingencies Disclosure [Line Items]
Other non-current liability																									$ 5,000,000
Indemnification agreement
Commitments And Contingencies Disclosure [Line Items]
Payment for legal settlement																			0
Performance guarantee | Private Placement
Commitments And Contingencies Disclosure [Line Items]
Other non-current liability										$ 6,500,000																$ 30,000,000
Rusnano Group | NeoPhotonics Corporation, LLC | Disposal Group, Not Discontinued Operations
Commitments And Contingencies Disclosure [Line Items]
Ownership to be disposed										100.00%
Consideration received pursuant to asset purchase agreement										$ 3,000,000
Penalty payment cancellation										$ 1,000,000
Oyster Communications, Inc.
Commitments And Contingencies Disclosure [Line Items]
New claims filed, number | lawsuit																9
Finisar Corp
Commitments And Contingencies Disclosure [Line Items]
Pending claims | claim																							2
Lestina International Ltd. litigation
Commitments And Contingencies Disclosure [Line Items]
Damages sought, value				$ 3,000,000
Lawsuit Filed By Lestina International Ltd. | NeoPhotonics Dongguan Co., Ltd | Lestina International Ltd.
Commitments And Contingencies Disclosure [Line Items]
Loss contingency, damages awarded, value								$ 2,200,000											2,200,000
Damages paid					$ 1,000,000		$ 1,200,000
APAT OE Legal Dispute
Commitments And Contingencies Disclosure [Line Items]
Damages sought, value															$ 20,000,000
APAT OE Legal Dispute | APAT OE
Commitments And Contingencies Disclosure [Line Items]
New claims filed, number | lawsuit									2	2
APAT OE And NeoChina
Commitments And Contingencies Disclosure [Line Items]
Damages sought, value									¥ 50,900	$ 7,600,000
Assets ordered to be preserved										$ 29,000,000
Claim Against APAT OE And Zheijiang Merchants Property Insurance Company | NeoChina
Commitments And Contingencies Disclosure [Line Items]
Damages sought, value						¥ 350	52,000
APAT Arbitration
Commitments And Contingencies Disclosure [Line Items]
Damages sought, value			$ 1,500,000				$ 7,100,000					$ 7,800,000		$ 12,000,000
Damages awarded to company	¥ 700	$ 110,000
Attorney fees											¥ 810	$ 121,000
Cisco Settlement Agreement
Commitments And Contingencies Disclosure [Line Items]
Loss contingency, damages awarded, value													$ 150,000						$ 300,000