Lease Obligations (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Jan. 03, 2015	Dec. 28, 2013	Dec. 29, 2012
Leases [Abstract]
Percentage of stores leased	53.00%swy_PercentageOfStoresLeased
Future minimum sublease rental income under non-cancelable capital and operating lease agreements	$ 145.9
Amortization expense for property under capital leases	73.7	46.1	26.3
Accumulated amortization of property under capital leases	$ 324.2	$ 251.9

Future minimum sublease rental income under non-cancelable capital and operating lease agreements

No definition available.

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- Definition

Percentage of stores leased

+ References

No definition available.

+ Details

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- Definition

The charge for the use of long-lived depreciable capital leased assets for the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6455314&loc=d3e45031-112735

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 840

-Section 55

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6501752&loc=d3e56872-110439

+ Details

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- Definition

The total charge for the use of long-lived depreciable assets subject to a lease meeting the criteria for capitalization.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6455314&loc=d3e45014-112735

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 10

-Section 55

-Paragraph 40

-Subparagraph (Note 2)

-URI http://asc.fasb.org/extlink&oid=6584154&loc=d3e38371-112697

+ Details

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- Details

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