Earnings (loss) per common share ("EPS") - Schedule of Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Feb. 02, 2019	Nov. 03, 2018	Aug. 04, 2018	May 05, 2018	Feb. 03, 2018	Oct. 28, 2017	Jul. 29, 2017	Apr. 29, 2017	Feb. 02, 2019	Feb. 03, 2018	Jan. 28, 2017
Equity [Abstract]
Net income (loss) attributable to common shareholders									$ (690.3)	$ 486.4	$ 531.3
Add: Dividends on preferred shares									0.0	32.9	11.9
Numerator for diluted EPS									$ (690.3)	$ 519.3	$ 543.2
Basic weighted average number of common shares outstanding									54.7	63.0	74.5
Dilutive effect of share awards (in shares)									0.0	0.1	0.1
Dilutive effect of preferred shares (in shares)									0.0	6.7	2.1
Diluted weighted average number of common shares outstanding									54.7	69.8	76.7
Earnings per share - basic (usd per share)	$ (2.25)	$ (0.74)	$ (0.56)	$ (8.48)	$ 5.70	$ (0.20)	$ 1.34	$ 1.03	$ (12.62)	$ 7.72	$ 7.13
Earnings per share - diluted (usd per share)	$ (2.25)	$ (0.74)	$ (0.56)	$ (8.48)	$ 5.24	$ (0.20)	$ 1.33	$ 1.03	$ (12.62)	$ 7.44	$ 7.08