Leases - Narrative (Details) $ in Thousands						1 Months Ended	3 Months Ended	9 Months Ended
	Aug. 14, 2020 USD ($)	Feb. 28, 2020 USD ($)	Jan. 31, 2020 USD ($)	Jun. 20, 2019 USD ($)	May 19, 2019 USD ($)	Jun. 20, 2019 USD ($)	Mar. 28, 2020 USD ($)	Sep. 26, 2020 USD ($) numberOfOptions	Sep. 28, 2019 USD ($)	Dec. 28, 2019 USD ($)	Dec. 29, 2018
Lessee, Lease, Description [Line Items]
Number of Options | numberOfOptions								1
Lease renewal term								5 years
Finance lease, renewal term											5 years
Finance lease obligations								$ 273,222		$ 198,011
Proceeds from real estate financing transactions								78,263	$ 44,725
Proceeds from sale of assets								$ 10,742	$ 13,699
Warehouse faciility
Lessee, Lease, Description [Line Items]
Finance lease, term of contract	5 years				15 years
Finance lease, renewal term	5 years				5 years			5 years
Finance lease obligations								$ 83,000		$ 85,800
Proceeds from real estate financing transactions		$ 7,500	$ 34,100			$ 45,000	$ 27,200	$ 78,300
Proceeds from sale of assets	$ 11,000
Net proceeds from sale of assets	10,600
Gain associated with sale-leaseback transactions	$ 8,700
Warehouse faciility | University Park, IL
Lessee, Lease, Description [Line Items]
Proceeds from real estate financing transactions					$ 21,800
Warehouse faciility | Yulee, FL
Lessee, Lease, Description [Line Items]
Proceeds from real estate financing transactions				$ 13,300
Minimum
Lessee, Lease, Description [Line Items]
Lease term								1 year
Finance lease, renewal term											10 years
Minimum | Warehouse faciility
Lessee, Lease, Description [Line Items]
Finance lease, term of contract								15 years
Maximum
Lessee, Lease, Description [Line Items]
Lease term								15 years
Finance lease, term of contract											15 years
Maximum | Warehouse faciility
Lessee, Lease, Description [Line Items]
Finance lease, term of contract								18 years