Cash, cash equivalents and short-term investments (Detail) - USD ($) $ in Thousands	Jan. 01, 2021	Jan. 03, 2020
Fair Value Measurements [Line Items]
Amortized Cost	$ 242,518	$ 231,277
Unrealized Gains	8	324
Unrealized Losses	0	0
Estimated Fair Value	242,526	231,601
Cash
Fair Value Measurements [Line Items]
Amortized Cost	146,083	135,225
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	146,083	135,225
Money market securities
Fair Value Measurements [Line Items]
Amortized Cost	51,442	41,211
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	51,442	41,211
Total cash equivalents
Fair Value Measurements [Line Items]
Amortized Cost	51,442	41,211
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	51,442	41,211
Total cash and cash equivalents
Fair Value Measurements [Line Items]
Amortized Cost	197,525	176,436
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	197,525	176,436
U.S. Treasury securities
Fair Value Measurements [Line Items]
Amortized Cost	44,993	54,841
Unrealized Gains	8	324
Unrealized Losses	0	0
Estimated Fair Value	45,001	55,165
Total short-term investments
Fair Value Measurements [Line Items]
Amortized Cost	44,993	54,841
Unrealized Gains	8	324
Unrealized Losses	0	0
Estimated Fair Value	$ 45,001	$ 55,165

Fair Value Measurements [Line Items]

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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