Employee Benefit Plans - Estimated Pre-Tax Amount to be Amortized from Accumulated Other Comprehensive Loss into Net Periodic Benefit Cost Over Next 12 Months (Details) $ in Millions	Jan. 31, 2019 USD ($)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 10.5
Prior service cost (credit)	0.1
Total before tax	10.6
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	0.0
Prior service cost (credit)	(0.7)
Total before tax	$ (0.7)