Debt Debt (Maximum Leverage Ratio Schedule) (Details)	3 Months Ended
	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016
Minimum [Member]
Debt Instrument [Line Items]
required total leverage ratio	550.00%	550.00%	550.00%	550.00%	550.00%	550.00%	550.00%
Maximum [Member]
Debt Instrument [Line Items]
required total leverage ratio	550.00%	595.00%	595.00%	605.00%	595.00%	595.00%	605.00%
Ferrellgas, L.P. [Member] | Minimum [Member]
Debt Instrument [Line Items]
required total leverage ratio	550.00%	550.00%	550.00%	550.00%	550.00%	550.00%	550.00%
Ferrellgas, L.P. [Member] | Maximum [Member]
Debt Instrument [Line Items]
required total leverage ratio	550.00%	595.00%	595.00%	605.00%	595.00%	595.00%	605.00%