Note 10 - Income Taxes (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%	21.00%	34.00%
Effective Income Tax Rate Reconciliation, at Highest Federal Statutory Income Tax Rate, Percent				35.00%
Tax Cuts and Jobs Act, Transition Tax for Accumulated Foreign Earnings, Liability, Total		$ 0
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		$ 31,674	$ 13,777	$ 39,907
Earnings Per Share, Tax Holiday Effect		$ (0.04)	$ (0.05)	$ 0.18
Unrecognized Tax Benefits that Would Impact Effective Tax Rate		$ 5,478
Decrease in Unrecognized Tax Benefits is Reasonably Possible		58
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Total		16	$ 17	$ 16
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total		56	65	113
Undistributed Earnings of Foreign Subsidiaries		31,008
Domestic Tax Authority [Member]
Operating Loss Carryforwards, Total		261,621
Tax Credit Carryforward, Amount		57,078
Domestic Tax Authority [Member] | Cortina Systems Inc. [Member]
Operating Loss Carryforwards, Total		49,152
Domestic Tax Authority [Member] | ClariPhy Communications Inc.[Member]
Operating Loss Carryforwards, Total		46,601
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member] | Cortina Systems Inc. [Member]
Tax Credit Carryforward, Amount		6,033
Domestic Tax Authority [Member] | Tax Year 2018 [Member]
Operating Loss Carryforwards, Total		59,407
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Total		96,559
Tax Credit Carryforward, Amount		58,288
State and Local Jurisdiction [Member] | Cortina Systems Inc. [Member]
Operating Loss Carryforwards, Total		3,919
State and Local Jurisdiction [Member] | ClariPhy Communications Inc.[Member]
Operating Loss Carryforwards, Total		68,104
State and Local Jurisdiction [Member] | Research Tax Credit Carryforward [Member] | Cortina Systems Inc. [Member]
Tax Credit Carryforward, Amount		7,912
Foreign Tax Authority [Member]
Increase (Decrease) in Income Taxes		(1,729)	(2,093)	7,412
Foreign Tax Authority [Member] | Tax Authority, Taiwan [Member]
Operating Loss Carryforwards, Total		2,597
Foreign Tax Authority [Member] | Her Majesty's Revenue and Customs (HMRC) [Member]
Operating Loss Carryforwards, Total		8,409
Foreign Tax Authority [Member] | Canada Revenue Agency [Member]
Tax Credit Carryforward, Amount		6,999
Foreign Tax Authority [Member] | Canada Revenue Agency [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount		$ 3,750
Foreign Tax Authority [Member] | Inland Revenue, Singapore (IRAS) [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		17.00%
Effective Income Tax Rate Reconciliation, Tax Holiday, Percent		5.00%
Open Tax Year		2010 2011 2012
Foreign Tax Authority [Member] | Administracion Federal de Ingresos Publicos (AFIP) [Member]
Effective Income Tax Rate Reconciliation, Tax Holiday, Percent		12.00%
Foreign Tax Authority [Member] | Administracion Federal de Ingresos Publicos (AFIP) [Member] | Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	30.00%
Increase to Income Tax Provision [Member]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		$ 31,917	13,757	39,931
Decrease to Other Comprehensive Income [Member]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		$ 243
Increase to Other Comprehensive Income [Member]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount			$ 20	134
Decrease to Goodwill [Member]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount				$ 158