Common shares, treasury shares, reserves and dividends - Share Repurchase (Details) - USD ($)	12 Months Ended
	Jan. 30, 2021	Feb. 01, 2020	Feb. 02, 2019
Class of Stock [Line Items]
Shares repurchased (shares)	0	0	8,800,000
Amount repurchased	$ 0	$ 0	$ 485,000,000.0
Average repurchase price per share (usd per share)	$ 0	$ 0.00	$ 55.06
2017 Program
Class of Stock [Line Items]
Stock repurchase program, authorized amount	$ 600,000,000.0
Shares repurchased (shares)	0	0	7,500,000
Amount repurchased	$ 0	$ 0	$ 434,400,000
Average repurchase price per share (usd per share)	$ 0	$ 0.00	$ 57.64
Remaining authorized repurchase amount	$ 165,600,000
2016 Program
Class of Stock [Line Items]
Stock repurchase program, authorized amount	$ 1,375,000,000.0
Shares repurchased (shares)			1,300,000
Amount repurchased			$ 50,600,000
Average repurchase price per share (usd per share)			$ 39.76