Share-based compensation - Significant Assumptions used to Estimate Fair Value of Awards under Omnibus Plan (Details) - Omnibus Plan - $ / shares	12 Months Ended
Feb. 01, 2020	Feb. 02, 2019	Feb. 03, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value per share of awards granted (usd per share)	$ 25.18
Restricted Stock and Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share price (usd per share)	$ 20.76	$ 41.36	$ 65.74
Expected term	2 years 9 months 18 days	2 years 9 months 18 days	2 years 8 months 12 days
Dividend yield	7.50%	3.60%	2.10%
Weighted average grant date fair value per share of awards granted (usd per share)	$ 18.14	$ 38.57	$ 63.42
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share price (usd per share)	22.17	40.09
Exercise price (usd per share)	$ 25.18	$ 39.72
Risk free interest rate	2.40%	2.90%
Expected term	6 years	6 years 6 months
Expected volatility	42.70%	37.60%
Dividend yield	6.70%	3.70%
Weighted average grant date fair value per share of awards granted (usd per share)	$ 4.27	$ 11.21

Share Based Compensation Arrangement by Share Based Payment Award, Fair Value Assumptions, Stock Price

No definition available.

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- Definition

Agreed-upon price for the exchange of the underlying asset relating to the share-based payment award.

+ References

No definition available.

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

+ References

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- Definition

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

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- Definition

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.

+ References

No definition available.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

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- Definition

Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

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