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Associate Retirement Plans - Additional Information (Detail) - USD ($) |  | 3 Months Ended | 4 Months Ended
--- | --- | --- | ---
Feb. 28, 2018 | Dec. 30, 2017 | Apr. 21, 2018
Defined Benefit Plan Disclosure [Line Items] |  |  |
Pension contributions during last plan year |  | $ 4,400,000 | $ 4,500,000
Pension Plan or Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
One-time, pre-tax settlement charge | $ 22,000,000 |  |
Pension Plan or Plan [Member] | Minimum [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expected termination process period |  |  | 12 months
Pension Plan or Plan [Member] | Maximum [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expected termination process period |  |  | 24 months
Retiree Medical Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expected Company contribution for remainder of fiscal year |  |  | $ 400,000
SpartanNash Company Pension Plan [Member] | Pension Plan or Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net periodic benefit (income) expense |  | (200,000) | (100,000)
Standard pension funding carryover |  |  | 0
SpartanNash Company Pension Plan [Member] | Pension Plan or Plan [Member] | Minimum [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expected Company contribution for remainder of fiscal year |  |  | 2,000,000
SpartanNash Company Pension Plan [Member] | Pension Plan or Plan [Member] | Maximum [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expected Company contribution for remainder of fiscal year |  |  | 3,000,000
SpartanNash Retiree Medical Plan [Member] | Retiree Medical Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Net periodic benefit (income) expense |  | $ 100,000 | $ 100,000

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