Guarantor financial information - Condensed Consolidated Statements of Earnings (Details) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2016	Oct. 31, 2015
Revenues:
Propane and other gas liquids sales	$ 242,399	$ 245,301
Midstream operations	108,044	193,670
Other	29,099	32,175
Total revenues	379,542	471,146
Costs and expenses:
Cost of product sold - propane and other gas liquids sales	119,212	121,751
Cost of sales - midstream operations	94,642	153,604
Cost of product sold - other	11,746	14,448
Operating expense	105,086	116,199
Depreciation and amortization expense	26,202	36,979
General and administrative expense	14,269	19,144
Equipment lease expense	7,349	7,032
Non-cash employee stock ownership plan compensation charge	3,754	5,256
Goodwill impairment	0	29,316
Loss on disposal of assets	6,423	14,917
Operating income (loss)	(9,141)	(47,500)
Interest expense	(35,428)	(33,788)
Other income (expense), net	508	(122)
Earnings (loss) before income taxes	(44,061)	(81,410)
Income tax expense	(590)	(844)
Net earnings (loss)	(43,471)	(80,566)
Other comprehensive income (loss)	9,376	8,610
Comprehensive income	(34,095)	(71,956)
Ferrellgas, L.P. [Member]
Revenues:
Propane and other gas liquids sales	242,399	245,301
Midstream operations	108,044	193,670
Other	29,099	32,175
Total revenues	379,542	471,146
Costs and expenses:
Cost of product sold - propane and other gas liquids sales	119,212	121,751
Cost of sales - midstream operations	94,642	153,604
Cost of product sold - other	11,746	14,448
Operating expense	105,086	116,199
Depreciation and amortization expense	26,202	36,979
General and administrative expense	14,269	19,144
Equipment lease expense	7,349	7,032
Non-cash employee stock ownership plan compensation charge	3,754	5,256
Asset Impairment Charges		29,316
Goodwill impairment	0	29,316
Loss on disposal of assets	6,423	14,917
Operating income (loss)	(9,141)	(47,500)
Interest expense	(31,398)	(29,758)
Other income (expense), net	508	(122)
Earnings (loss) before income taxes	(40,031)	(77,380)
Income tax expense	(591)	(844)
Equity in earnings of subsidiary	0	0
Net earnings (loss)	(39,440)	(76,536)
Other comprehensive income (loss)	9,376	8,610
Comprehensive income	(30,064)	(67,926)
Reportable Legal Entities [Member] | Ferrellgas, L.P. (Parent and Co-Issuer) [Member]
Revenues:
Propane and other gas liquids sales	242,399	245,301
Midstream operations	0	0
Other	17,326	17,377
Total revenues	259,725	262,678
Costs and expenses:
Cost of product sold - propane and other gas liquids sales	119,212	121,748
Cost of sales - midstream operations	0	0
Cost of product sold - other	2,430	2,538
Operating expense	97,655	96,974
Depreciation and amortization expense	18,277	18,550
General and administrative expense	12,863	17,429
Equipment lease expense	7,210	6,882
Non-cash employee stock ownership plan compensation charge	3,754	5,256
Asset Impairment Charges		0
Loss on disposal of assets	1,447	1,545
Operating income (loss)	(3,123)	(8,244)
Interest expense	(20,352)	(18,521)
Other income (expense), net	(47)	(122)
Earnings (loss) before income taxes	(23,522)	(26,887)
Income tax expense	(29)	168
Equity in earnings of subsidiary	(15,947)	(49,481)
Net earnings (loss)	(39,440)	(76,536)
Other comprehensive income (loss)	9,376	8,610
Comprehensive income	(30,064)	(67,926)
Reportable Legal Entities [Member] | Ferrellgas Finance Corp. (Co-Issuer) [Member]
Revenues:
Propane and other gas liquids sales	0	0
Midstream operations	0	0
Other	0	0
Total revenues	0	0
Costs and expenses:
Cost of product sold - propane and other gas liquids sales	0	0
Cost of sales - midstream operations	0	0
Cost of product sold - other	0	0
Operating expense	0	0
Depreciation and amortization expense	0	0
General and administrative expense	2	3
Equipment lease expense	0	0
Non-cash employee stock ownership plan compensation charge	0	0
Asset Impairment Charges		0
Loss on disposal of assets	0	0
Operating income (loss)	(2)	(3)
Interest expense	0	0
Other income (expense), net	0	0
Earnings (loss) before income taxes	(2)	(3)
Income tax expense	0	0
Equity in earnings of subsidiary	0	0
Net earnings (loss)	(2)	(3)
Other comprehensive income (loss)	0	0
Comprehensive income	(2)	(3)
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Revenues:
Propane and other gas liquids sales	0	0
Midstream operations	108,044	193,670
Other	11,773	14,798
Total revenues	119,817	208,468
Costs and expenses:
Cost of product sold - propane and other gas liquids sales	0	3
Cost of sales - midstream operations	94,642	153,604
Cost of product sold - other	9,316	11,910
Operating expense	10,246	17,659
Depreciation and amortization expense	7,872	18,429
General and administrative expense	1,404	1,712
Equipment lease expense	139	150
Non-cash employee stock ownership plan compensation charge	0	0
Asset Impairment Charges		29,316
Loss on disposal of assets	4,976	13,372
Operating income (loss)	(8,778)	(37,687)
Interest expense	(10,673)	(10,688)
Other income (expense), net	555	0
Earnings (loss) before income taxes	(18,896)	(48,375)
Income tax expense	(562)	(1,012)
Equity in earnings of subsidiary	0	0
Net earnings (loss)	(18,334)	(47,363)
Other comprehensive income (loss)	0	0
Comprehensive income	(18,334)	(47,363)
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Revenues:
Propane and other gas liquids sales	0	0
Midstream operations	0	0
Other	0	0
Total revenues	0	0
Costs and expenses:
Cost of product sold - propane and other gas liquids sales	0	0
Cost of sales - midstream operations	0	0
Cost of product sold - other	0	0
Operating expense	(2,105)	2,370
Depreciation and amortization expense	53	0
General and administrative expense	0	0
Equipment lease expense	0	0
Non-cash employee stock ownership plan compensation charge	0	0
Asset Impairment Charges		0
Loss on disposal of assets	0	0
Operating income (loss)	2,052	(2,370)
Interest expense	(370)	(441)
Other income (expense), net	707	696
Earnings (loss) before income taxes	2,389	(2,115)
Income tax expense	0	0
Equity in earnings of subsidiary	0	0
Net earnings (loss)	2,389	(2,115)
Other comprehensive income (loss)	0	0
Comprehensive income	2,389	(2,115)
Eliminations [Member]
Revenues:
Propane and other gas liquids sales	0	0
Midstream operations	0	0
Other	0	0
Total revenues	0	0
Costs and expenses:
Cost of product sold - propane and other gas liquids sales	0	0
Cost of sales - midstream operations	0	0
Cost of product sold - other	0	0
Operating expense	(710)	(804)
Depreciation and amortization expense	0	0
General and administrative expense	0	0
Equipment lease expense	0	0
Non-cash employee stock ownership plan compensation charge	0	0
Asset Impairment Charges		0
Loss on disposal of assets	0	0
Operating income (loss)	710	804
Interest expense	(3)	(108)
Other income (expense), net	(707)	(696)
Earnings (loss) before income taxes	0	0
Income tax expense	0	0
Equity in earnings of subsidiary	15,947	49,481
Net earnings (loss)	15,947	49,481
Other comprehensive income (loss)	0	0
Comprehensive income	$ 15,947	$ 49,481