Guarantor financial information Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Current assets:
Cash and cash equivalents	$ 5,760	$ 4,965	$ 7,652	$ 8,289
Accounts and notes receivable, net	165,084	149,583
Inventories	92,552	90,594
Prepaid expenses and other current assets	33,388	39,973
Total current assets	296,784	285,115
Property, plant and equipment, net	731,923	774,680
Goodwill	256,103	256,103	478,747
Intangible assets, net	251,102	280,185
Other assets, net	74,057	87,223
Total assets	1,609,969	1,683,306
Current liabilities:
Accounts payable	85,561	67,928
Short-term borrowings	59,781	101,291
Collateralized note payable	69,000	64,000
Other current liabilities	126,224	128,958
Total current liabilities	340,566	362,177
Long-term debt	1,995,795	1,941,335
Other liabilities	31,118	31,574
Contingencies and commitments
Partners' capital (deficit)
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	(757,510)	(651,780)	207,709	(111,646)
Accumulated other comprehensive income (loss)	14,601	(10,468)
Total liabilities and partners' capital (deficit)	1,609,969	1,683,306
Total Ferrellgas Partners, L.P. partners' capital (deficit)	(753,578)	(647,057)
Parent Company [Member]
Current assets:
Cash and cash equivalents	59	75	2,052	6
Prepaid expenses and other current assets	4	18
Total assets	63	93
Current liabilities:
Other current liabilities	4,250	2,006
Long-term debt	346,525	180,454
Partners' capital (deficit)
Accumulated other comprehensive income (loss)	14,601	(10,468)
Total liabilities and partners' capital (deficit)	63	93
Total Ferrellgas Partners, L.P. partners' capital (deficit)	(753,578)	(647,057)
Ferrellgas, L.P. [Member]
Current assets:
Cash and cash equivalents	5,701	4,890	5,600	8,283
Accounts and notes receivable, net	165,084	149,583
Intercompany Receivables, Current	0	0
Inventories	92,552	90,594
Prepaid expenses and other current assets	33,426	39,955
Total current assets	296,763	285,022
Property, plant and equipment, net	731,923	774,680
Goodwill	256,103	256,103	478,747
Intangible assets, net	251,102	280,185
Intercompany Receivables, Noncurrent	0	0
Investment in Ferrellgas, L.P.	0	0
Other assets, net	74,057	87,223
Total assets	1,609,948	1,683,213
Current liabilities:
Accounts payable	85,561	67,928
Short-term borrowings	59,781	101,291
Collateralized note payable	69,000	64,000
Intercompany Payables	0	0
Other current liabilities	122,016	126,952
Total current liabilities	336,358	360,171
Long-term debt	1,649,270	1,760,881
Other liabilities	31,118	31,574
Contingencies and commitments
Partners' capital (deficit)
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	(406,798)	(469,413)	390,126	69,925
Accumulated other comprehensive income (loss)	14,764	(10,560)
Total liabilities and partners' capital (deficit)	1,609,948	1,683,213
Total Ferrellgas Partners, L.P. partners' capital (deficit)	(421,562)	(458,853)
Reportable Legal Entities [Member] | Parent Company [Member]
Current assets:
Cash and cash equivalents	5,327	4,472	5,579	7,798
Accounts and notes receivable, net	(3,132)	(2,703)
Intercompany Receivables, Current	39,877	34,089
Inventories	78,963	71,422
Prepaid expenses and other current assets	26,106	27,922
Total current assets	147,141	135,202
Property, plant and equipment, net	537,582	557,460
Goodwill	246,098	246,098
Intangible assets, net	128,209	141,794
Intercompany Receivables, Noncurrent	450,000	450,000
Investment in Ferrellgas, L.P.	(53,915)	3,630
Other assets, net	35,862	37,742
Total assets	1,490,977	1,571,926
Current liabilities:
Accounts payable	44,026	33,781
Short-term borrowings	59,781	101,291
Collateralized note payable	0	0
Intercompany Payables	0	0
Other current liabilities	118,039	119,048
Total current liabilities	221,846	254,120
Long-term debt	1,649,139	1,759,868
Other liabilities	26,790	27,351
Partners' capital (deficit)
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	(406,798)	(469,413)
Accumulated other comprehensive income (loss)	14,764	(10,560)
Total liabilities and partners' capital (deficit)	1,490,977	1,571,926
Total Ferrellgas Partners, L.P. partners' capital (deficit)	(421,562)	(458,853)
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	373	417	20	484
Accounts and notes receivable, net	58,618	45,822
Intercompany Receivables, Current	0	0
Inventories	13,589	19,172
Prepaid expenses and other current assets	7,314	12,029
Total current assets	79,894	77,440
Property, plant and equipment, net	194,341	217,220
Goodwill	10,005	10,005
Intangible assets, net	122,893	138,391
Intercompany Receivables, Noncurrent	0	0
Investment in Ferrellgas, L.P.	0	0
Other assets, net	37,618	49,016
Total assets	444,751	492,072
Current liabilities:
Accounts payable	41,345	34,147
Short-term borrowings	0	0
Collateralized note payable	0	0
Intercompany Payables	41,645	35,491
Other current liabilities	3,776	7,754
Total current liabilities	86,766	77,392
Long-term debt	450,131	451,013
Other liabilities	4,300	3,998
Partners' capital (deficit)
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	(96,446)	(40,331)
Accumulated other comprehensive income (loss)	0	(647)
Total liabilities and partners' capital (deficit)	444,751	492,072
Total Ferrellgas Partners, L.P. partners' capital (deficit)	(96,446)	(39,684)
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	0	0	0	0
Accounts and notes receivable, net	109,598	106,464
Intercompany Receivables, Current	0	0
Inventories	0	0
Prepaid expenses and other current assets	6	2
Total current assets	109,604	106,466
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Intercompany Receivables, Noncurrent	0	0
Investment in Ferrellgas, L.P.	0	0
Other assets, net	577	465
Total assets	110,181	106,931
Current liabilities:
Accounts payable	190	0
Short-term borrowings	0	0
Collateralized note payable	69,000	64,000
Intercompany Payables	(1,768)	(1,402)
Other current liabilities	201	150
Total current liabilities	67,623	62,748
Long-term debt	0	0
Other liabilities	28	225
Partners' capital (deficit)
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	42,530	43,958
Accumulated other comprehensive income (loss)	0	325
Total liabilities and partners' capital (deficit)	110,181	106,931
Total Ferrellgas Partners, L.P. partners' capital (deficit)	42,530	43,633
Reportable Legal Entities [Member] | Co-issuer [Member]
Current assets:
Cash and cash equivalents	1	1	1	1
Accounts and notes receivable, net	0	0
Intercompany Receivables, Current	0	0
Inventories	0	0
Prepaid expenses and other current assets	0	2
Total current assets	1	3
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Intercompany Receivables, Noncurrent	0	0
Investment in Ferrellgas, L.P.	0	0
Other assets, net	0	0
Total assets	1	3
Current liabilities:
Accounts payable	0	0
Short-term borrowings	0	0
Collateralized note payable	0	0
Intercompany Payables	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Long-term debt	0	0
Other liabilities	0	0
Partners' capital (deficit)
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	1	3
Accumulated other comprehensive income (loss)	0	0
Total liabilities and partners' capital (deficit)	1	3
Total Ferrellgas Partners, L.P. partners' capital (deficit)	1	3
Eliminations [Member]
Current assets:
Cash and cash equivalents	0	0	$ 0	$ 0
Accounts and notes receivable, net	0	0
Intercompany Receivables, Current	(39,877)	(34,089)
Inventories	0	0
Prepaid expenses and other current assets	0	0
Total current assets	(39,877)	(34,089)
Property, plant and equipment, net	0	0
Goodwill	0	0
Intangible assets, net	0	0
Intercompany Receivables, Noncurrent	(450,000)	(450,000)
Investment in Ferrellgas, L.P.	53,915	(3,630)
Other assets, net	0	0
Total assets	(435,962)	(487,719)
Current liabilities:
Accounts payable	0	0
Short-term borrowings	0	0
Collateralized note payable	0	0
Intercompany Payables	(39,877)	(34,089)
Other current liabilities	0	0
Total current liabilities	(39,877)	(34,089)
Long-term debt	(450,000)	(450,000)
Other liabilities	0	0
Partners' capital (deficit)
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	53,915	(3,630)
Accumulated other comprehensive income (loss)	0	322
Total liabilities and partners' capital (deficit)	(435,962)	(487,719)
Total Ferrellgas Partners, L.P. partners' capital (deficit)	$ 53,915	$ (3,952)