Debt - Interest Rate Swaps (Details) - USD ($) $ in Thousands		12 Months Ended
	May 03, 2018	Jul. 31, 2018	Jul. 31, 2019	May 31, 2018	Apr. 30, 2018	Jul. 31, 2017	May 31, 2012	Nov. 30, 2010
Debt Instrument [Line Items]
Derivative, Notional Amount				$ 100,000	$ 100,000	$ 175,000	$ 140,000
Swap Termination Payment	$ 4,200	$ 4,200
Derivative Asset, Fair Value, Gross Asset	4,200	$ 22,470	$ 1,259
Derivative, Fixed Interest Rate							6.50%
Derivative variable interest rate				1.95%		1.95%	4.715%
Fixed Rate 6.5% Due 2021
Debt Instrument [Line Items]
Aggregate principal amount							$ 500,000	$ 500,000
Interest rate, as a percent		6.50%					6.50%	6.50%
Derivative variable interest rate							4.715%
Ferrellgas, L.P. [Member]
Debt Instrument [Line Items]
Derivative, Notional Amount				$ 100,000		$ 175,000	$ 140,000
Swap Termination Payment	4,200	$ 4,200
Derivative Asset, Fair Value, Gross Asset	$ 4,200	$ 22,470	$ 1,259
Derivative, Fixed Interest Rate				1.95%		1.95%	6.50%
Ferrellgas, L.P. [Member] | Fixed Rate 6.5% Due 2021
Debt Instrument [Line Items]
Aggregate principal amount							$ 500,000	$ 500,000
Interest rate, as a percent			6.50%				6.50%	6.50%
Derivative variable interest rate							4.715%