Fair Value Measurements - Other Financial Instruments (Details) - USD ($) $ in Millions	Jul. 31, 2019	Jul. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable, fair value	$ 15.5
Notes receivable, carrying amount in excess of fair value	0.7
Long-term debt, fair value	1,824.6	$ 1,935.1
Ferrellgas, L.P. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable, fair value	15.5
Notes receivable, carrying amount in excess of fair value	0.7
Long-term debt, fair value	$ 1,562.2	$ 1,591.5