Asset Sale (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		12 Months Ended
	Jan. 31, 2017	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Apr. 30, 2019	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring charges		$ 0	$ 179
Gain within operating income				$ 900		$ 2,200
Transition services agreement receivable		11,680		11,861
Transition services agreement payables		11,759		$ 11,765
Other Current Liabilities | Indemnification Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset sale related contingent liabilities		$ 6,500
NeoPhotonics Corporation, LLC | Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percent of interest to be disposed					100.00%
Restructuring charges					$ 1,600
Accrued payment derivative					2,000
Assets-held-for sale					$ 3,000
Percent of ownership disposed							100.00%
Consideration received pursuant to asset purchase agreement							$ 2,000
Exit fee settlements							$ 2,000
Low Speed Transceiver Products | Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets-held-for sale								$ 13,900
Assets held for sale, inventory								13,100
Assets held for sale, property, plant and equipment								$ 800
Reclassification from assets held-for-sale	$ 3,400
Assets sold	12,800
Low Speed Transceiver Products | Disposed of by Sale | APAT OE
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received pursuant to asset purchase agreement	25,000
Proceeds from post-closing transaction services fees under transition services agreement	1,400
Disposal group consideration adjustment	21,600
Consideration adjustment for potential indemnification claims	10,000
Low Speed Transceiver Products | Disposed of by Sale | Inventories
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets sold	12,100
Low Speed Transceiver Products | Disposed of by Sale | Property, Plant and Equipment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets sold	$ 700