Commitments and Contingencies - Narrative (Details)				3 Months Ended
	Dec. 08, 2017 USD ($)	Nov. 03, 2017 USD ($) plaintiff	Feb. 07, 2017 plaintiff	Jul. 31, 2018 USD ($)	Aug. 01, 2018 USD ($)
Loss Contingencies [Line Items]
Standby letters of credit				$ 155,500,000
Surety bonds				$ 454,700,000	$ 2,700,000
Subsidiary ownership interest (in percent)				33.00%
Loss contingency amount accrued for probable losses				$ 11,700,000
Litigation losses				3,800,000
Energy Savings Contracts
Loss Contingencies [Line Items]
Guarantee obligation				176,000,000
Performance Guarantee | Joint Venture
Loss Contingencies [Line Items]
Total guarantees				35,000,000
Hussein And Isse
Loss Contingencies [Line Items]
Loss contingency amount accrued for probable losses				3,800,000
Settlement amount		$ 8,300,000
Isse
Loss Contingencies [Line Items]
Number of plaintiffs | plaintiff		220	60
Payments for legal settlements	$ 4,500,000
Minimum
Loss Contingencies [Line Items]
Amount of reasonably possible loss				0
Maximum
Loss Contingencies [Line Items]
Amount of reasonably possible loss				$ 4,000,000