Retirement Benefit Plans - Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax, Portion Attributable to Parent [Abstract]
Prior service credit for period	$ 0.0	$ (2.2)	$ 0.0
Effect of settlement	(1.1)	0.0	0.0
Net loss (gain) for period	7.2	9.1	18.4
Amortization of prior service credit	0.3	0.1	0.1
Amortization of net loss	(1.7)	(1.4)	(0.6)
Other comprehensive loss (income)	$ 4.7	$ 5.6	$ 17.9