Fair value measurements - Estimated fair value of long-term debt, including current maturities (Details) - Level 2 - USD ($)
$ in Thousands
Sep. 26, 2020
Mar. 28, 2020
Sep. 28, 2019
Fair value measurements      
Total fair value of debt $ 237,811 $ 285,365 $ 291,811
The 2019 Elfa Revolving Credit Facility      
Fair value measurements      
Total fair value of debt 1,107 9,050 10,813
Revolving credit facility      
Fair value measurements      
Total fair value of debt   78,000 26,000
Senior secured term loan facility      
Fair value measurements      
Total fair value of debt 236,431 198,041 254,729
Obligations under capital leases      
Fair value measurements      
Total fair value of debt $ 273 $ 274 $ 269