Income taxes - Additional Information (Detail) - USD ($) |
12 Months Ended | |
|---|---|---|
Mar. 28, 2020 |
Mar. 30, 2019 |
|
| Tax Credit Carryforward [Line Items] | ||
| Non cash valuation allowance | $ 22,475,000 | $ 19,276,000 |
| Earliest Tax Year [Member] | ||
| Tax Credit Carryforward [Line Items] | ||
| Open tax year | 2013 | |
| Latest Tax Year [Member] | ||
| Tax Credit Carryforward [Line Items] | ||
| Open tax year | 2020 | |
| Domestic Tax Authority [Member] | ||
| Tax Credit Carryforward [Line Items] | ||
| Federal non capital losses | $ 53,500,000 | |
| Domestic Tax Authority [Member] | Investment Tax Credit Carryforward [Member] | ||
| Tax Credit Carryforward [Line Items] | ||
| Capital losses | 260,000 | |
| Domestic Tax Authority [Member] | Capital Loss Carryforward [Member] | ||
| Tax Credit Carryforward [Line Items] | ||
| Capital losses | $ 1,400,000 |