Goodwill and intangibles - Composition of Finite-Lived Intangibles (Details) (USD $) In Millions, unless otherwise specified	May 02, 2015	Jan. 31, 2015	May 03, 2014
Definite-lived intangible assets:
Gross carrying amount	$ 50.1	$ 49.6
Accumulated amortization	(12.9)	(9.3)
Net carrying amount	37.2us-gaap_FiniteLivedIntangibleAssetsNet	40.3us-gaap_FiniteLivedIntangibleAssetsNet
Intangible assets, gross	458.8	456.4
Total intangible assets, net	445.9	447.1	0
Definite-lived intangible liabilities:
Gross carrying amount	(114.7)us-gaap_BelowMarketLeaseGross	(114.3)us-gaap_BelowMarketLeaseGross
Accumulated amortization	32.3	23.5
Total	(82.4)us-gaap_BelowMarketLeaseNet	(90.8)us-gaap_BelowMarketLeaseNet
Unfavorable leases
Definite-lived intangible liabilities:
Gross carrying amount	(49.1)	(48.7)
Accumulated amortization	13.3	9.7
Total	(35.8)	(39.0)
Unfavorable contracts
Definite-lived intangible liabilities:
Gross carrying amount	(65.6)	(65.6)
Accumulated amortization	19.0	13.8
Total	(46.6)	(51.8)
Trade names
Definite-lived intangible assets:
Gross carrying amount	1.5	1.5
Accumulated amortization	(0.3)	(0.2)
Net carrying amount	1.2	1.3
Favorable leases
Definite-lived intangible assets:
Gross carrying amount	48.6	48.1
Accumulated amortization	(12.6)	(9.1)
Net carrying amount	36.0	39.0
Trade names
Definite-lived intangible assets:
Indefinite-lived trade names	$ 408.7	$ 406.8

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Amount of accumulated amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life.

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Amount before amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life.

+ References

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Amount after amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life.

+ References

No definition available.

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- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

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

-Publisher FASB

-Name Accounting Standards Codification

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Amount before accumulated amortization of intangible assets, excluding goodwill.

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

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