Shareholders' equity - Dividends (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
May 01, 2021	May 02, 2020
Dividends Payable [Line Items]
Dividends declared per preferred share (usd per share)	$ 13.14	$ 12.50
Dividends, preferred stock, paid-in-kind	$ 8.2	$ 7.8
Series A Redeemable Convertible Preferred Stock \| Accrued expenses and other current liabilities
Dividends Payable [Line Items]
Dividends payable	$ 8.2	$ 7.8

Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
-Paragraph 8
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of paid and unpaid preferred stock dividends declared with the form of settlement in payment-in-kind (PIK).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 405
-Section 45
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-URI http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817

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Aggregate dividends declared during the period for each share of preferred stock outstanding.

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