Associate Retirement Plans - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 11, 2020	Jul. 13, 2019	Jul. 11, 2020	Jul. 13, 2019
Defined Benefit Plan Disclosure [Line Items]
Pension contributions during last plan year	$ 3.5	$ 3.4	$ 8.1	$ 8.2
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income) expense		8.8	1.0	9.2
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		$ 0.3
SpartanNash Retiree Medical Plan [Member] | Retiree Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income) expense		$ 0.1		$ 0.2