Commitments and Contingencies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011
Commitments and Contingencies Disclosure [Abstract]
Purchase commitments not completed at year end	$ 571.8

Purchase Commitment, Remaining Minimum Amount Committed, Long-term and Short-term

No definition available.

Name:	swy_PurchaseCommitmentRemainingMinimumAmountCommittedLongTermAndShortTerm
Namespace Prefix:	swy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant