Segment reporting - Sales by merchandise category as a percentage of total net sales (Details)	12 Months Ended
	Mar. 28, 2020	Mar. 30, 2019	Mar. 31, 2018
Sales by merchandise category as a percentage of total net sales
Merchandise category as a percentage of total net sales	100.00%	100.00%	100.00%
Net sales | Sales by merchandise category | Custom Closets
Sales by merchandise category as a percentage of total net sales
Merchandise category as a percentage of total net sales	51.00%	49.00%	48.00%
Net sales | Sales by merchandise category | Storage, Box, Shelving
Sales by merchandise category as a percentage of total net sales
Merchandise category as a percentage of total net sales	13.00%	14.00%	14.00%
Net sales | Sales by merchandise category | Kitchen and Trash
Sales by merchandise category as a percentage of total net sales
Merchandise category as a percentage of total net sales	14.00%	14.00%	13.00%
Net sales | Sales by merchandise category | Office, Collections, Hooks
Sales by merchandise category as a percentage of total net sales
Merchandise category as a percentage of total net sales	8.00%	8.00%	8.00%
Net sales | Sales by merchandise category | Bath, Travel, Laundry
Sales by merchandise category as a percentage of total net sales
Merchandise category as a percentage of total net sales	7.00%	8.00%	8.00%
Net sales | Sales by merchandise category | Containers, Gift Packaging, Seasonal, Impulse
Sales by merchandise category as a percentage of total net sales
Merchandise category as a percentage of total net sales	5.00%	6.00%	7.00%
Net sales | Sales by merchandise category | Other
Sales by merchandise category as a percentage of total net sales
Merchandise category as a percentage of total net sales	2.00%	1.00%	2.00%