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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