Consolidated Statements Of Shareholders' Equity - USD ($) $ in Millions	Total	Common shares at par value	Additional paid-in capital	Other reserves	Treasury shares	Retained earnings	Accumulated other comprehensive (loss) income
Balance at Jan. 31, 2015	$ 2,810.4	$ 15.7	$ 265.2	$ 0.4	$ (370.0)	$ 3,135.7	$ (236.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	467.9	0.0	0.0	0.0	0.0	467.9	0.0
Other comprehensive income (loss)	(37.5)	0.0	0.0	0.0	0.0	0.0	(37.5)
Dividends on common shares	(70.2)	0.0	0.0	0.0	0.0	(70.2)	0.0
Repurchase of common shares	(130.0)	0.0	0.0	0.0	(130.0)	0.0	0.0
Net settlement of equity based awards	(1.3)	0.0	(1.5)	0.0	(1.1)	1.3	0.0
Share options exercised	5.0	0.0	(0.2)	0.0	5.3	(0.1)	0.0
Share-based compensation expense	16.4	0.0	16.4	0.0	0.0	0.0	0.0
Balance at Jan. 30, 2016	3,060.7	15.7	279.9	0.4	(495.8)	3,534.6	(274.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	543.2	0.0	0.0	0.0	0.0	543.2	0.0
Other comprehensive income (loss)	(33.6)	0.0	0.0	0.0	0.0	0.0	(33.6)
Dividends on common shares	(75.9)	0.0	0.0	0.0	0.0	(75.9)	0.0
Dividends on redeemable convertible preferred shares	(11.9)					(11.9)
Repurchase of common shares	(1,000.0)	0.0	0.0	0.0	(1,000.0)	0.0	0.0
Net settlement of equity based awards	(2.4)	0.0	(7.2)	0.0	(1.1)	5.9	0.0
Share options exercised	2.1	0.0	0.0	0.0	2.1	0.0	0.0
Share-based compensation expense	8.0	0.0	8.0	0.0	0.0	0.0	0.0
Balance at Jan. 28, 2017	2,490.2	15.7	280.7	0.4	(1,494.8)	3,995.9	(307.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	519.3	0.0	0.0	0.0	0.0	519.3	0.0
Other comprehensive income (loss)	47.1	0.0	0.0	0.0	0.0	0.0	47.1
Dividends on common shares	(77.5)	0.0	0.0	0.0	0.0	(77.5)	0.0
Dividends on redeemable convertible preferred shares	(32.9)					(32.9)
Repurchase of common shares	(460.0)	0.0	0.0	0.0	(460.0)	0.0	0.0
Net settlement of equity based awards	(2.8)	0.0	(6.5)	0.0	12.3	(8.6)	0.0
Share options exercised	0.3	0.0	(0.1)	0.0	0.4	0.0	0.0
Share-based compensation expense	16.1	0.0	16.1	0.0	0.0	0.0	0.0
Balance at Feb. 03, 2018	$ 2,499.8	$ 15.7	$ 290.2	$ 0.4	$ (1,942.1)	$ 4,396.2	$ (260.6)