Acquisitions (Narrative) (Details) $ in Thousands			2 Months Ended	3 Months Ended	6 Months Ended
	Oct. 30, 2016 USD ($) store	Aug. 01, 2016 USD ($) store	Oct. 30, 2016 USD ($) store site	Jul. 01, 2017 USD ($)	Jul. 01, 2017 USD ($)	Dec. 31, 2016 USD ($)
Acquisitions [Line Items]
Goodwill				$ 52,330	$ 52,330	$ 52,330
Mars Super Market [Member]
Acquisitions [Line Items]
Sales				22,700	45,900
Number of stores acquired | store		5
Purchase price		$ 24,600
Goodwill		$ 13,300
Number of lease obligations assumed		2
Number of new lease agreements due to acquisition		2
Food Lion, LLC [Member]
Acquisitions [Line Items]
Sales				95,200	188,900
Number of stores acquired | store			38
Number of owned stores acquired | site			8
Purchase price			$ 29,400
Gain on bargain purchase			$ 23,900
Number of lease obligations assumed			30
Food Lion, LLC [Member] | MARYLAND
Acquisitions [Line Items]
Number of stores acquired | store			21
Food Lion, LLC [Member] | DELAWARE
Acquisitions [Line Items]
Number of stores acquired | store			4
Food Lion, LLC [Member] | VIRGINIA
Acquisitions [Line Items]
Number of stores acquired | store			13
Nell's Family Market [Member]
Acquisitions [Line Items]
Sales				$ 4,600	$ 8,700
Number of stores acquired | store	1
Purchase price	$ 13,000
Purchase price payable	3,400
Purchase price payable, term					4 years
Goodwill	$ 3,900		$ 3,900