Net Income (Loss) Per Share - Numerators and Denominators of Basic and Diluted Net Income (Loss) Per Share Computations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2018		Sep. 28, 2018		Jun. 29, 2018		Mar. 30, 2018		Dec. 31, 2017		Sep. 29, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator:
Net loss	$ 3,330	[1],[2],[3]	$ (7,758)	[1],[2],[3]	$ (2,913)	[1],[2],[3]	$ (13,694)	[1],[2],[3]	$ (11,516)	[2],[3]	$ (15,583)	[2],[3]	$ (31,500)	[2],[3]	$ (24,027)	[2],[3]	$ (21,035)	$ (82,955)	$ (72,314)
Denominator:
Basic and diluted									82,014		81,445		80,590		79,810		85,615	80,974	77,705
Net loss per share, Basic and diluted
Basic and diluted	$ 0.04		$ (0.09)		$ (0.03)		$ (0.16)		$ (0.14)		$ (0.19)		$ (0.39)		$ (0.30)		$ (0.25)	$ (1.02)	$ (0.93)

[1] During the fourth quarter of 2018, the Company recorded net income primarily due to higher revenues with stronger gross margins of 53.1% coupled with reduced operating expenses as a result of our vigilant cost management.

[2] During the fourth quarter of 2018, the Company released $1.0 million of valuation allowance associated with one of Company’s foreign subsidiaries. During the third and fourth quarter of 2017, the Company recorded $2.4 million of tax benefit associated with the release of tax reserves for uncertain tax positions as a result of the expiration of statute of limitations and $2.5 million of tax benefits associated with the alternative minimum tax refund related to the TCJA, respectively. These tax benefits were offset by $3.0 million tax expense recorded during the fourth quarter of 2017, related to tax law changes in one of the Company’s foreign subsidiaries.

[3] In 2017, the Company incurred TVN acquisition- and integration-related expenses of $2.2 million, $0.5 million, $0.1 million and $0.1 million during the first through fourth quarter of 2017. These costs consisted of acquisition-related costs which include outside legal, accounting and other professional services as well as integration-related costs which include incremental costs resulting from the TVN acquisition that are not expected to generate future benefits once the integration is fully consummated. These costs are expensed as incurred and the Company did not incur any TVN acquisition- and integration-related expenses in 2018.