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

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Date the declared dividend will be paid, in CCYY-MM-DD format.

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

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Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding.

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Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format.

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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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No definition available.

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Amount of paid and unpaid preferred stock dividends declared with the form of settlement in cash.

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Adjustment to retained earnings for the increase in carrying amount of redeemable preferred stock that is classified as temporary equity.

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Shareholders' equity - Dividends (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended				6 Months Ended
	Aug. 29, 2017	Jul. 29, 2017	Apr. 29, 2017	Jul. 30, 2016	Apr. 30, 2016	Jul. 29, 2017	Jul. 30, 2016
Dividends Payable [Line Items]
Dividends declared per share (usd per share)		$ 0.31	$ 0.31	$ 0.26	$ 0.26	$ 0.62	$ 0.52
Dividends, common stock		$ 18.7	$ 21.3	$ 19.7	$ 20.4	$ 40.0	$ 40.1
Dividends on redeemable convertible preferred shares						16.4
Subsequent Event
Dividends Payable [Line Items]
Dividends declared per share (usd per share)	$ 0.31
Dividends payable date	Nov. 30, 2017
Dividends payable, date of record	Oct. 27, 2017
Series A Redeemable Convertible Preferred Stock
Dividends Payable [Line Items]
Cash dividends declared		7.8				15.6
Dividends on preferred shares		7.8				7.8
Dividends on redeemable convertible preferred shares		$ 0.4				$ 0.8