Condensed Statements Of Shareholders' Equity - 9 months ended Oct. 31, 2015 - 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 (loss)	196.0	0.0	0.0	0.0	0.0	196.0	0.0
Other comprehensive loss	(9.2)	0.0	0.0	0.0	0.0	0.0	(9.2)
Dividends	(52.7)	0.0	0.0	0.0	0.0	(52.7)	0.0
Repurchase of common shares	(111.9)	0.0	0.0	0.0	(111.9)	0.0	0.0
Net settlement of equity based awards	(2.7)	0.0	(3.0)	0.0	(1.1)	1.4	0.0
Share options exercised	3.3	0.0	0.7	0.0	2.7	(0.1)	0.0
Share-based compensation expense	11.8	0.0	11.8	0.0	0.0	0.0	0.0
Balance at Oct. 31, 2015	$ 2,845.0	$ 15.7	$ 274.7	$ 0.4	$ (480.3)	$ 3,280.3	$ (245.8)