Commitments and Contingencies - Narrative (Details) $ in Millions				1 Months Ended
	Dec. 20, 2018 USD ($)	Nov. 03, 2017 USD ($) plaintiff	Feb. 07, 2017 plaintiff	Jan. 31, 2019 USD ($)	Jan. 31, 2018 USD ($)	Jul. 31, 2019 USD ($)
Loss Contingencies [Line Items]
Standby letters of credit						$ 152.4
Subsidiary ownership interest (in percent)						33.00%
Surety Bonds
Loss Contingencies [Line Items]
Surety bonds						$ 607.7
Surety Bond - Future Effective Date
Loss Contingencies [Line Items]
Surety bonds						1.3
Energy Savings Contracts
Loss Contingencies [Line Items]
Guarantee obligation						175.5
Performance Guarantee | Joint Venture
Loss Contingencies [Line Items]
Total guarantees						35.0
Minimum
Loss Contingencies [Line Items]
Amount of reasonably possible loss						0.0
Maximum
Loss Contingencies [Line Items]
Amount of reasonably possible loss						5.0
Settled Litigation | Isse
Loss Contingencies [Line Items]
Number of plaintiffs | plaintiff		220	60
Payments for legal settlements					$ 4.5
Settled Litigation | Hussein And Isse
Loss Contingencies [Line Items]
Settlement amount		$ 8.3
Settled Litigation | Hussein
Loss Contingencies [Line Items]
Settlement amount	$ 2.1
Settled Litigation | Hussein, Opt-Out
Loss Contingencies [Line Items]
Settlement amount				$ 1.2
Pending Litigation
Loss Contingencies [Line Items]
Loss contingency amount accrued for probable losses						12.1
Pending Litigation | Castro
Loss Contingencies [Line Items]
Loss contingency amount accrued for probable losses						$ 5.4