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Associate Retirement Plans - Additional Information (Detail) - USD ($) |  | 3 Months Ended | 9 Months Ended
--- | --- | --- | ---
Feb. 28, 2018 | Oct. 06, 2018 | Oct. 07, 2017 | Oct. 06, 2018 | Oct. 07, 2017
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Pension contributions during last plan year |  | $ 2,100,000 | $ 2,400,000 | $ 10,000,000 | $ 10,200,000
Pension Plan or Plan [Member] |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Frozen pension plan, termination date |  |  |  | Jul. 31, 2018 |
Pension Plan or Plan [Member] | Minimum [Member] |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Distribution of assets to plan participants, expected period |  |  |  | 6 months |
One-time, pre-tax settlement charge | $ 20,000,000 |  |  |  |
Pension Plan or Plan [Member] | Maximum [Member] |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Distribution of assets to plan participants, expected period |  |  |  | 18 months |
One-time, pre-tax settlement charge | $ 21,000,000 |  |  |  |
Retiree Medical Plan [Member] |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Expected Company contribution for remainder of fiscal year |  | 400,000 |  | $ 400,000 |
SpartanNash Company Pension Plan [Member] | Pension Plan or Plan [Member] |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Net periodic benefit (income) expense |  | (100,000) | (100,000) | (300,000) | (500,000)
Standard pension funding carryover |  | 1,500,000 |  | 1,500,000 |
Expected Company contribution for remainder of fiscal year |  | 0 |  | 0 |
SpartanNash Retiree Medical Plan [Member] | Retiree Medical Plan [Member] |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Net periodic benefit (income) expense |  | $ 100,000 | $ 100,000 | $ 400,000 | $ 300,000

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