Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	Jan. 31, 2019	Jul. 31, 2018
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 1,825.1	$ 1,935.1
Level 2 [Member] | Ferrellgas, L.P. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	1,560.0	$ 1,591.5
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable, fair value	24.2
Notes receivable, carrying amount in excess of fair value	3.4
Fair Value, Inputs, Level 3 [Member] | Ferrellgas, L.P. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes receivable, fair value	24.2
Notes receivable, carrying amount in excess of fair value	$ 3.4