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Retirement Plans - Narrative (Detail) £ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | ---
Dec. 25, 2020 USD ($) | Dec. 27, 2019 USD ($) | Dec. 25, 2020 USD ($) | Dec. 27, 2019 USD ($) | Mar. 27, 2020 USD ($) | Mar. 29, 2019 USD ($) | Dec. 25, 2020 GBP (£) | Mar. 27, 2020 GBP (£) | Mar. 29, 2019 GBP (£)
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Actuarial net gain or loss included in AOCI, expected to be amortized into net periodic benefit cost over the next fiscal year |  |  |  |  | $ 0 |  |  |  |
Pension Plan |  |  |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Company contributions | $ 249,000 | $ 235,000 | $ 736,000 | $ 698,000 | 943,000 |  |  |  |
Expected contributions in current fiscal year |  |  |  |  | $ 943,000 |  |  |  |
Other Defined Benefit Plan | Pension Promise |  |  |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Retirement age |  |  | 65 |  | 65 |  |  |  |
Accrued retirement, other long-term liabilities | 1,112,000 |  | $ 1,112,000 |  | $ 975,000 | $ 975,000 | £ 827 | £ 866 | £ 866
Other assets, net | 1,112,000 |  | $ 1,112,000 |  | 975,000 | 975,000 | £ 827 | 866 | £ 866
Other Defined Benefit Plan | Previously Reported | Pension Promise |  |  |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Accrued retirement, other long-term liabilities |  |  |  |  | 978,000 |  |  | 903 |
Other assets, net |  |  |  |  | $ 978,000 |  |  | £ 903 |
Defined Contribution Plan |  |  |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Maximum employee contribution |  |  | 50.00% |  | 50.00% |  |  |  |
Employer matching contribution |  |  | 100.00% |  | 100.00% |  |  |  |
Maximum employer contribution |  |  | 5.00% |  | 5.00% |  |  |  |
Total contributions | 1,112,000 | 833,000 | $ 3,181,000 | 2,840,000 | $ 3,792,000 | 4,019,000 |  |  |
Defined Contribution Plan | AME Plan |  |  |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Total contributions |  |  |  |  | $ 372,000 | 451,000 |  |  |
Defined Contribution Plan | 401(K) Plan |  |  |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Maximum employee contribution |  |  | 35.00% |  | 35.00% |  |  |  |
Employer matching contribution |  |  | 100.00% |  | 100.00% |  |  |  |
Maximum employer contribution |  |  | 5.00% |  | 5.00% |  |  |  |
Total contributions |  | 376,000 |  | 1,310,000 | $ 1,828,000 | $ 1,921,000 |  |  |
Vesting percentage |  |  | 100.00% |  | 100.00% |  |  |  |
Safe Harbor Provision, employer contribution |  |  | 3.00% |  | 3.00% |  |  |  |
Defined Contribution Plan | AME Plan |  |  |  |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Total contributions | $ 207,000 | $ 201,000 | $ 592,000 | $ 560,000 |  |  |  |  |

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