Condensed parent only debtor in possession financial information - Income Statements (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jan. 31, 2021	Oct. 31, 2020	Jan. 31, 2020	Oct. 31, 2019	Jan. 31, 2021	Jan. 31, 2020
Condensed Income Statements, Captions [Line Items]
General and administrative expense	$ 20,475		$ 14,192		$ 33,555	$ 23,887
Interest expense	52,595		47,548		106,821	93,245
Reorganization expense - professional fees	1,200				1,200
Total expenses	(114,604)		(96,378)		(122,356)	(97,008)
Loss before income taxes and equity in earnings of non-debtor entities	64,317		48,906		17,951	3,707
Income tax expense (benefit)	326		115		413	633
Net earnings (loss)	63,991	$ (46,453)	48,791	$ (45,717)	17,538	3,074
Net earnings (loss) attributable to noncontrolling interest	724		584		333	211
Net earnings (loss)	63,267		48,207		17,205	2,863
Other comprehensive income (loss)	28,516	$ 7,917	(2,555)	$ (6,148)	36,433	(8,703)
Comprehensive income (loss) attributable to Ferrellgas Partners, LP	92,219		$ 45,679		53,603	$ (5,751)
Debtor In Possession [Member]
Condensed Income Statements, Captions [Line Items]
General and administrative expense	221				225
Interest expense	6,324				14,022
Reorganization expense - professional fees	1,200				1,200
Total expenses	7,745				15,447
Loss before income taxes and equity in earnings of non-debtor entities	(7,745)				(15,447)
Income tax expense (benefit)	14				14
Equity in earnings (loss) of Ferrellgas, L.P.	71,750				32,999
Net earnings (loss)	63,991				17,538
Net earnings (loss) attributable to noncontrolling interest	724				333
Net earnings (loss)	63,267				17,205
Comprehensive income (loss) attributable to Ferrellgas Partners, LP	$ 63,267				$ 17,205