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Associate Retirement Plans - Additional Information (Detail) - USD ($) $ in Millions | 3 Months Ended | 4 Months Ended | 6 Months Ended
--- | --- | --- | ---
Jul. 17, 2021 | Jul. 11, 2020 | Apr. 18, 2020 | Jul. 17, 2021 | Jul. 11, 2020
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Pension contributions during last plan year | $ 3.4 | $ 3.5 |  | $ 8.0 | $ 8.1
Pension Plan [Member] |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Net periodic benefit (income) expense |  |  | $ 1.0 |  |
Retiree Medical Plan [Member] |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Expected Company contribution for remainder of fiscal year | 0.5 |  |  | 0.5 |
Standard pension funding carryover |  |  |  | 0.2 |
SpartanNash Retiree Medical Plan Plan [Member] | Pension Plan [Member] |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Net periodic benefit (income) expense | $ 0.1 | $ 0.1 |  | $ 0.3 | $ 0.3

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