Nature of business and summary of significant accounting policies - Gift cards and merchandise credits (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 28, 2020	Mar. 30, 2019	Mar. 31, 2018
Gift cards and merchandise credits
Period of estimated performance	48 months
Gift card breakage recorded	$ 955	$ 942	$ 1,656
Advertising
Catalog and direct mailings costs capitalized	49	669
Advertising expense incurred	39,583	34,791	$ 32,860
Income taxes
Uncertain tax positions requiring accrual	0	0
Accounts receivable
Allowances for doubtful accounts	$ 326	$ 57