Fair Value Measurements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018
Assets:
Convertible note	$ 0	$ 2,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	(2,000)
Recurring | Level 1
Assets:
Corporate and government bonds, $17,016 at cost (3)	0	0
Convertible note		0
Derivative instruments (Note 11)	0	0
Total assets measured at fair value	0	3,730
Liabilities:
Derivative instruments (Note 11)	0	0
Total liabilities measured at fair value	0	0
Recurring | Level 1 | Money market funds
Assets:
Money market funds		3,730
Recurring | Level 2
Assets:
Corporate and government bonds, $17,016 at cost (3)	17,032	29,605
Convertible note		0
Derivative instruments (Note 11)	15,314	776
Total assets measured at fair value	32,346	30,381
Liabilities:
Derivative instruments (Note 11)	758	1,130
Total liabilities measured at fair value	758	1,130
Recurring | Level 2 | Money market funds
Assets:
Money market funds		0
Recurring | Level 3 (2)
Assets:
Corporate and government bonds, $17,016 at cost (3)	0	0
Convertible note		2,000
Derivative instruments (Note 11)	0	0
Total assets measured at fair value	0	2,000
Liabilities:
Derivative instruments (Note 11)	0	0
Total liabilities measured at fair value	$ 0	0
Recurring | Level 3 (2) | Money market funds
Assets:
Money market funds		$ 0