Income Taxes - Additional Information (Detail) - USD ($)		3 Months Ended	6 Months Ended	12 Months Ended
	Jan. 01, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016		Mar. 31, 2017	Dec. 31, 2015
Debt Instrument, Face Amount		$ 128,250,000	$ 128,250,000	$ 128,250,000	$ 128,250,000					$ 128,250,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				21.00%	35.00%		35.00%
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount				$ (1,449,000)	$ 2,834,000		$ (4,465,000)
Effective Income Tax Rate Reconciliation, Tax Settlement, Other, Amount				305,000	834,000
World Consolidated Loss Before Tax				16,948,000	84,707,000	[1]	80,430,000	[1]
Income Tax Expense (Benefit)				$ 4,087,000	$ (1,752,000)		$ (8,116,000)
Effective Income Tax Rate Reconciliation, Percent				(24.00%)	2.00%		10.00%
Deferred Tax Assets, Valuation Allowance		77,144,000	77,756,000	$ 77,144,000	$ 77,756,000		$ 74,480,000			$ 64,545,000
Decrease in balance as a result of a lapse of the applicable statues of limitations			2,400,000	100,000	2,200,000		1,000,000
Gross unrecognized tax benefits including interest and penalties		16,600,000		16,600,000
Accrued potential interest related to unrecognized tax benefits		24,000	500,000	24,000	500,000
Cumulative Undistributed Earnings of non-U.S. subsidiaries intended to be indefinitely reinvested		$ 15,300,000		$ 15,300,000
More Likely Than Not Threshold Recognition of Uncertain Tax Position		50.00%		50.00%
Deferred Tax Assets, Net		$ 8,695,000	$ 10,462,000	$ 8,695,000	10,462,000
US Tax Cuts Jobs Act [Member] | AMT credit carryover [Member]
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount					2,600,000
Foreign [Member]
Operating Loss Carryforwards		95,900,000		95,900,000
Federal [Member]
Operating Loss Carryforwards		38,000,000		38,000,000
Tax credit carryovers		13,200,000		$ 13,200,000
Year that federal tax credits expire				Jan. 01, 2031
California Franchise Tax Board [Member]
Operating Loss Carryforwards		21,600,000		$ 21,600,000
Tax credit carryovers		34,900,000		34,900,000
State [Member]
Operating Loss Carryforwards		48,000,000		$ 48,000,000
Tax credit expiration				will not expire
Switzerland [Member]
Tax savings due to reduction in tax rate				$ 400,000	$ 600,000		$ 700,000
Increase in diluted earnings per share				$ 0.005	$ 0.007		$ 0.008
Benefits from a tax ruling				The Company’s operations in Switzerland are subject to a reduced tax rate under the Switzerland tax holiday which requires various thresholds of investment and employment in Switzerland.
Additional period for renewal for investment and employment in foreign country				effective through the end of 2018
SEC Schedule, 12-09, Valuation Allowance, Operating Loss Carryforward [Member]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount				$ 900,000
Foreign [Member]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		$ (1,000,000)		$ (1,500,000)
Minimum [Member] | Federal [Member]
Operating loss carryforwards, expiration date				Jan. 01, 2026
Minimum [Member] | California Franchise Tax Board [Member]
Operating loss carryforwards, expiration date				Jan. 01, 2026
Maximum [Member] | Federal [Member]
Operating loss carryforwards, expiration date				Jan. 01, 2039
Maximum [Member] | California Franchise Tax Board [Member]
Operating loss carryforwards, expiration date				Jan. 01, 2039
US Tax Cuts Jobs Act [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				21.00%
One-time transition tax on foreign sourced earnings				$ 0
Accounting Standards Update 2016-16 [Member]
Deferred Tax Assets, Valuation Allowance									$ 2,100,000
Deferred Tax Assets, Tax Deferred Expense									300,000
Cumulative Effect on Retained Earnings, Net of Tax	$ 1,434,000
Deferred Tax Assets, Net									$ 1,100,000
Deferred Tax Assets Gross [Member] | Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	4,600,000
Retained Earnings [Member] | Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	$ 0

[1] For the years ended December 31, 2017 and 2016, the unallocated corporate expenses included TVN acquisition- and integration-related costs, TVN VDP costs (see Note 10, “Restructuring and Related charges-TVN VDP,” for more information on TVN VDP ) and Cable Access product line inventory obsolescence costs, totaling $7.9 million and $32.2 million, respectively. In addition, in fiscal 2017, the unallocated corporate expenses included $8.0 million of Avid litigation settlement cost and associated legal fees (see Note 19, “Legal Proceedings,” for more information). The remaining unallocated corporate expenses for all years presented above include primarily other restructuring charges and excess facilities charges.