Note 17 -Stock-based Compensation Plans - Summary of Option Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Number of Stock Options Outstanding (in shares)	879,338	657,209
Weighted-Average Exercise Price (in dollars per share)	$ 21.41	$ 18.21
Weighted-Average Remaining Contractual Life (Year)	4 years 219 days	4 years 255 days	4 years 328 days
Aggregate Intrinsic Value	$ 20.2	$ 8.7	$ 5.7
Granted, shares (in shares)	367,173	272,144	274,500
Granted, weighted-average exercise price (in dollars per share)	$ 38.06	$ 27.96
Exercised, shares (in shares)	(94,970)	(46,065)
Exercised, weighted-average exercise price (in dollars per share)	$ 15.62	$ 11.75
Forfeited, shares (in shares)	(23,719)	(3,950)
Forfeited, weighted-average exercise price (in dollars per share)	$ 31.93	$ 26.43
Number of Stock Options Outstanding (in shares)	1,127,822	879,338	657,209
Weighted-Average Exercise Price (in dollars per share)	$ 26.82	$ 21.41	$ 18.21
Vested or expected to vest, shares (in shares)	1,127,822
Vested or expected to vest, weighted-average exercise price (in dollars per share)	$ 26.82
Vested or expected to vest, weighted-average remaining contractual life (Year)	4 years 219 days
Vested or expected to vest, aggregate intrinsic value	$ 20.2
Exercisable, shares (in shares)	718,169
Exercisable, weighted-average exercise price (in dollars per share)	$ 22.88
Exercisable, weighted-average remaining contractual life (Year)	4 years
Exercisable, aggregate intrinsic value	$ 15.7

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of share options (or share units) exercised during the current period.

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