Forgivable Loans (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 28, 2020	Dec. 28, 2019
Forgivable Loans
Allowances for forgivable loans	$ 0	$ 0
Amount of forgivable loans written-off	0	0
Forgivable loan activity
Beginning balance	55,141	40,294
Advances	33,442	35,166
Repayments		(1,173)
Reclassification from accrued expenses / to other assets	(9,713)	(1,734)
Amortization	(6,285)	(17,700)
Effects of foreign currency translation	(540)	288
Ending balance	72,045	55,141
Current portion of forgivable loans	14,177	6,751
Non-current portion of forgivable loans	$ 57,868	$ 48,390