Retirement Benefit Plans - Allocation of Plan Assets (Details) - USD ($) $ in Millions	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	$ 80.8	$ 121.1	$ 107.4
Fair Value, Measurements, Recurring
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	80.8	121.1
Fair Value, Measurements, Recurring | Level 1, 2 and 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	42.5	70.0
Fair Value, Measurements, Recurring | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0.0
Fair Value, Measurements, Recurring | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	42.5
Fair Value, Measurements, Recurring | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0.0
Fair Value, Measurements, Recurring | Insurance contracts
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	28.0	53.0
Fair Value, Measurements, Recurring | Insurance contracts | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0.0
Fair Value, Measurements, Recurring | Insurance contracts | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	28.0
Fair Value, Measurements, Recurring | Insurance contracts | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0.0
Fair Value, Measurements, Recurring | Other investments
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	14.5	17.0
Fair Value, Measurements, Recurring | Other investments | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0.0
Fair Value, Measurements, Recurring | Other investments | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	14.5
Fair Value, Measurements, Recurring | Other investments | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0.0
Fair Value, Measurements, Recurring | Cash
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	4.3	0.2
Fair Value, Measurements, Recurring | Investment Fund | Net Asset Value
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	$ 34.0	$ 50.9