Restructuring and Related Costs - Cumulative Restructuring and Related Charges (Details) $ in Millions	Apr. 30, 2019 USD ($)
Restructuring Cost and Reserve [Line Items]
Cumulative charges	$ 96.4
GCA and Other Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative charges	29.9
2020 Vision Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative charges	66.5
External Support Fees
Restructuring Cost and Reserve [Line Items]
Cumulative charges	32.0
External Support Fees | GCA and Other Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative charges	2.0
External Support Fees | 2020 Vision Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative charges	30.0
Employee Severance
Restructuring Cost and Reserve [Line Items]
Cumulative charges	29.5
Employee Severance | GCA and Other Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative charges	16.6
Employee Severance | 2020 Vision Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative charges	13.0
Other Project Fees
Restructuring Cost and Reserve [Line Items]
Cumulative charges	21.3
Other Project Fees | GCA and Other Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative charges	10.6
Other Project Fees | 2020 Vision Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative charges	10.7
Lease Exit Costs
Restructuring Cost and Reserve [Line Items]
Cumulative charges	8.4
Lease Exit Costs | GCA and Other Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative charges	0.7
Lease Exit Costs | 2020 Vision Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative charges	7.7
Asset Impairment
Restructuring Cost and Reserve [Line Items]
Cumulative charges	5.2
Asset Impairment | GCA and Other Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative charges	0.0
Asset Impairment | 2020 Vision Restructuring Program
Restructuring Cost and Reserve [Line Items]
Cumulative charges	$ 5.2