Retirement Benefit Plans - Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax, Portion Attributable to Parent [Abstract]
Prior service credit for period	$ (2.2)	$ 0.0	$ 0.0
Net loss (gain) for period	9.1	18.4	(3.9)
Amortization of prior service credit	0.1	0.1	0.1
Amortization of net loss	(1.4)	(0.6)	(1.0)
Other comprehensive loss (income)	$ 5.6	$ 17.9	$ (4.8)