Guarantor financial information - Condensed Consolidated Statements of Earnings (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Revenues:
Propane and other gas liquids sales	$ 437,375	$ 376,856	$ 679,774	$ 622,157
Midstream operations	96,787	188,333	204,831	382,003
Other	45,088	84,049	74,187	116,224
Total revenues	579,250	649,238	958,792	1,120,384
Costs and expenses:
Cost of product sold - propane and other gas liquids sales	235,029	174,829	354,241	296,580
Cost of sales - midstream operations	87,024	148,443	181,666	302,047
Cost of product sold - other	20,657	55,774	32,403	70,222
Operating expense	113,076	115,997	218,162	232,196
Depreciation and amortization expense	25,607	37,367	51,809	74,346
General and administrative expense	12,279	10,072	26,548	29,216
Equipment lease expense	7,416	7,278	14,765	14,310
Non-cash employee stock ownership plan compensation charge	2,945	3,141	6,699	8,397
Goodwill impairment	0	0	0	29,316
Loss on disposal of assets	45	2,524	6,468	17,441
Operating income (loss)	75,172	93,813	66,031	46,313
Interest expense	(36,819)	(34,730)	72,247	68,518
Other income (expense), net	763	(298)	1,271	(420)
Earnings (loss) before income taxes	39,116	58,785	(4,945)	(22,625)
Income tax expense	588	1,030	(2)	186
Net earnings (loss)	38,528	57,755	(4,943)	(22,811)
Other comprehensive income (loss)	15,776	(2,937)	25,152	5,673
Comprehensive income	54,304	54,818	20,209	(17,138)
Ferrellgas, L.P. [Member]
Revenues:
Propane and other gas liquids sales	437,375	376,856	679,774	622,157
Midstream operations	96,787	188,333	204,831	382,003
Other	45,088	84,049	74,187	116,224
Total revenues	579,250	649,238	958,792	1,120,384
Costs and expenses:
Cost of product sold - propane and other gas liquids sales	235,029	174,829	354,241	296,580
Cost of sales - midstream operations	87,024	148,443	181,666	302,047
Cost of product sold - other	20,657	55,774	32,403	70,222
Operating expense	113,076	115,997	218,162	232,196
Depreciation and amortization expense	25,607	37,367	51,809	74,346
General and administrative expense	12,278	9,674	26,547	28,818
Equipment lease expense	7,416	7,278	14,765	14,310
Non-cash employee stock ownership plan compensation charge	2,945	3,141	6,699	8,397
Goodwill impairment	0	0	0	29,316
Loss on disposal of assets	45	2,524	6,468	17,441
Operating income (loss)	75,173	94,211	66,032	46,711
Interest expense	(32,748)	(30,701)	64,146	60,459
Other income (expense), net	763	(298)	1,271	(420)
Earnings (loss) before income taxes	43,188	63,212	3,157	(14,168)
Income tax expense	588	1,025	(3)	181
Equity in earnings of subsidiary	0	0	0	0
Net earnings (loss)	42,600	62,187	3,160	(14,349)
Other comprehensive income (loss)	15,776	(2,937)	25,152	5,673
Comprehensive income	58,376	59,250	28,312	(8,676)
Reportable Legal Entities [Member] | Ferrellgas, L.P. (Parent and Co-Issuer) [Member]
Revenues:
Propane and other gas liquids sales	437,375	376,856	679,774	622,157
Midstream operations	0	0	0	0
Other	21,609	21,571	38,935	38,948
Total revenues	458,984	398,427	718,709	661,105
Costs and expenses:
Cost of product sold - propane and other gas liquids sales	235,029	174,832	354,241	296,580
Cost of sales - midstream operations	0	0	0	0
Cost of product sold - other	2,571	2,257	5,001	4,795
Operating expense	103,986	101,688	201,641	198,662
Depreciation and amortization expense	18,014	18,805	36,291	37,355
General and administrative expense	11,093	8,306	23,956	25,735
Equipment lease expense	7,267	7,161	14,477	14,043
Non-cash employee stock ownership plan compensation charge	2,945	3,141	6,699	8,397
Goodwill impairment				0
Loss on disposal of assets	(73)	(2,100)	(1,520)	(3,645)
Operating income (loss)	78,006	80,137	74,883	71,893
Interest expense	(21,089)	(19,630)	(41,441)	(38,151)
Other income (expense), net	304	(298)	257	(420)
Earnings (loss) before income taxes	57,221	60,209	33,699	33,322
Income tax expense	103	110	74	278
Equity in earnings of subsidiary	(14,518)	2,088	(30,465)	(47,393)
Net earnings (loss)	42,600	62,187	3,160	(14,349)
Other comprehensive income (loss)	15,776	(2,937)	25,152	5,673
Comprehensive income	58,376	59,250	28,312	(8,676)
Reportable Legal Entities [Member] | Ferrellgas Finance Corp. (Co-Issuer) [Member]
Revenues:
Propane and other gas liquids sales	0	0	0	0
Midstream operations	0	0	0	0
Other	0	0	0	0
Total revenues	0	0	0	0
Costs and expenses:
Cost of product sold - propane and other gas liquids sales	0	0	0	0
Cost of sales - midstream operations	0	0	0	0
Cost of product sold - other	0	0	0	0
Operating expense	0	0	0	0
Depreciation and amortization expense	0	0	0	0
General and administrative expense	3	0	5	3
Equipment lease expense	0	0	0	0
Non-cash employee stock ownership plan compensation charge	0	0	0	0
Goodwill impairment				0
Loss on disposal of assets	0	0	0	0
Operating income (loss)	(3)	0	(5)	(3)
Interest expense	0	0	0	0
Other income (expense), net	0	0	0	0
Earnings (loss) before income taxes	(3)	0	(5)	(3)
Income tax expense	0	0	0	0
Equity in earnings of subsidiary	0	0	0	0
Net earnings (loss)	(3)	0	(5)	(3)
Other comprehensive income (loss)	0	0	0	0
Comprehensive income	(3)	0	(5)	(3)
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Revenues:
Propane and other gas liquids sales	0	0	0	0
Midstream operations	96,787	188,333	204,831	382,003
Other	23,479	62,478	35,252	77,276
Total revenues	120,266	250,811	240,083	459,279
Costs and expenses:
Cost of product sold - propane and other gas liquids sales	0	(3)	0	0
Cost of sales - midstream operations	87,024	148,443	181,666	302,047
Cost of product sold - other	18,086	53,517	27,402	65,427
Operating expense	9,642	14,722	19,888	32,381
Depreciation and amortization expense	7,527	18,562	15,399	36,991
General and administrative expense	1,182	1,368	2,586	3,080
Equipment lease expense	149	117	288	267
Non-cash employee stock ownership plan compensation charge	0	0	0	0
Goodwill impairment				29,316
Loss on disposal of assets	28	(424)	(4,948)	(13,796)
Operating income (loss)	(3,316)	13,661	(12,094)	(24,026)
Interest expense	(11,002)	(10,632)	(21,675)	(21,320)
Other income (expense), net	459	0	1,014	0
Earnings (loss) before income taxes	(13,859)	3,029	(32,755)	(45,346)
Income tax expense	485	915	(77)	(97)
Equity in earnings of subsidiary	0	0	0	0
Net earnings (loss)	(14,344)	2,114	(32,678)	(45,249)
Other comprehensive income (loss)	0	0	0	0
Comprehensive income	(14,344)	2,114	(32,678)	(45,249)
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Revenues:
Propane and other gas liquids sales	0	0	0	0
Midstream operations	0	0	0	0
Other	0	0	0	0
Total revenues	0	0	0	0
Costs and expenses:
Cost of product sold - propane and other gas liquids sales	0	0	0	0
Cost of sales - midstream operations	0	0	0	0
Cost of product sold - other	0	0	0	0
Operating expense	539	235	(1,566)	2,605
Depreciation and amortization expense	66	0	119	0
General and administrative expense	0	0	0	0
Equipment lease expense	0	0	0	0
Non-cash employee stock ownership plan compensation charge	0	0	0	0
Goodwill impairment				0
Loss on disposal of assets	0	0	0	0
Operating income (loss)	(605)	(235)	1,447	(2,605)
Interest expense	(657)	(692)	(1,027)	(1,133)
Other income (expense), net	1,091	901	1,798	1,597
Earnings (loss) before income taxes	(171)	(26)	2,218	(2,141)
Income tax expense	0	0	0	0
Equity in earnings of subsidiary	0	0	0	0
Net earnings (loss)	(171)	(26)	2,218	(2,141)
Other comprehensive income (loss)	0	0	0	0
Comprehensive income	(171)	(26)	2,218	(2,141)
Eliminations [Member]
Revenues:
Propane and other gas liquids sales	0	0	0	0
Midstream operations	0	0	0	0
Other	0	0	0	0
Total revenues	0	0	0	0
Costs and expenses:
Cost of product sold - propane and other gas liquids sales	0	0	0	0
Cost of sales - midstream operations	0	0	0	0
Cost of product sold - other	0	0	0	0
Operating expense	(1,091)	(648)	(1,801)	(1,452)
Depreciation and amortization expense	0	0	0	0
General and administrative expense	0	0	0	0
Equipment lease expense	0	0	0	0
Non-cash employee stock ownership plan compensation charge	0	0	0	0
Goodwill impairment				0
Loss on disposal of assets	0	0	0	0
Operating income (loss)	1,091	648	1,801	1,452
Interest expense	0	253	(3)	145
Other income (expense), net	(1,091)	(901)	(1,798)	(1,597)
Earnings (loss) before income taxes	0	0	0	0
Income tax expense	0	0	0	0
Equity in earnings of subsidiary	14,518	(2,088)	30,465	47,393
Net earnings (loss)	14,518	(2,088)	30,465	47,393
Other comprehensive income (loss)	0	0	0	0
Comprehensive income	$ 14,518	$ (2,088)	$ 30,465	$ 47,393