Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair value, measurements, recurring - USD ($) $ in Thousands	Dec. 28, 2019	Dec. 29, 2018
Assets
Total assets	$ 0	$ 60,845
Money market funds
Assets
Total assets	0	10,347
Corporate bonds
Assets
Total assets	0	23,512
U.S. agency notes
Assets
Total assets	0	2,999
U.S. treasuries
Assets
Total assets	0	23,987
Foreign currency exchange forward contracts
Liabilities
Total liabilities	(159)	(91)
Level 1
Assets
Total assets	0	34,334
Level 1 | Money market funds
Assets
Total assets	0	10,347
Level 1 | Corporate bonds
Assets
Total assets	0	0
Level 1 | U.S. agency notes
Assets
Total assets	0	0
Level 1 | U.S. treasuries
Assets
Total assets	0	23,987
Level 1 | Foreign currency exchange forward contracts
Liabilities
Total liabilities	0	0
Level 2
Assets
Total assets	0	26,511
Level 2 | Money market funds
Assets
Total assets	0	0
Level 2 | Corporate bonds
Assets
Total assets	0	23,512
Level 2 | U.S. agency notes
Assets
Total assets	0	2,999
Level 2 | U.S. treasuries
Assets
Total assets	0	0
Level 2 | Foreign currency exchange forward contracts
Liabilities
Total liabilities	$ (159)	$ (91)