Derivative Financial Instruments (Details 4) - USD ($) $ in Millions	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jul. 31, 2017
Commodity contracts
Outstanding derivative contracts
Gross contract notional amount	$ 949.1		$ 658.0
Foreign currency exchange contracts
Outstanding derivative contracts
Gross contract notional amount	64.0		122.1
Treasury Lock [Member]
Outstanding derivative contracts
Gross contract notional amount				$ 300.0
Interest rate contract
Outstanding derivative contracts
Gross contract notional amount	$ 500.0	$ 500.0	$ 0.0