Derivative Instruments and Hedging Activities - AOCI Rollforward (Details)	12 Months Ended			36 Months Ended
	Jul. 31, 2019 USD ($) MMBbls	Jul. 31, 2018 USD ($)	Jul. 31, 2017 USD ($)	Jul. 31, 2019 USD ($)
Derivative [Line Items]
Partners' capital balance, beginning	$ (1,034,477,000)	$ (757,510,000)	$ (651,780,000)	$ (651,780,000)
Change in value of derivative	(48,184,000)	30,231,000	22,525,000
Reclassification of (gains) losses on derivatives to earnings, net	12,868,000	(24,319,000)	1,938,000
Partners' capital balance, ending	(1,138,938,000)	(1,034,477,000)	(757,510,000)	(1,138,938,000)
Reclassification of net losses to earnings during next 12 months	$ (13,300,000)
Gain (loss) on discontinuation of cash flow hedge due to forecasted transaction probable of not occurring, net			0	0
Number of barrels of propane covered by cash flow hedges | MMBbls	4.9
Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Derivative [Line Items]
Partners' capital balance, beginning	$ 20,560,000	14,648,000	(9,815,000)	(9,815,000)
Partners' capital balance, ending	(14,756,000)	20,560,000	14,648,000	(14,756,000)
Ferrellgas, L.P. [Member]
Derivative [Line Items]
Partners' capital balance, beginning	(680,078,000)	(406,798,000)	(469,413,000)	(469,413,000)
Change in value of derivative	(48,184,000)	30,231,000	22,525,000
Reclassification of (gains) losses on derivatives to earnings, net	12,868,000	(24,319,000)	1,938,000
Partners' capital balance, ending	(780,403,000)	(680,078,000)	(406,798,000)	(780,403,000)
Reclassification of net losses to earnings during next 12 months	$ (13,300,000)
Gain (loss) on discontinuation of cash flow hedge due to forecasted transaction probable of not occurring, net				0
Number of barrels of propane covered by cash flow hedges | MMBbls	4.9
Ferrellgas, L.P. [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Derivative [Line Items]
Partners' capital balance, beginning	$ 20,560,000	14,648,000	(9,815,000)	(9,815,000)
Partners' capital balance, ending	(14,756,000)	20,560,000	14,648,000	$ (14,756,000)
Commodity Derivatives Propane [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Derivative [Line Items]
Change in value of derivative	(48,184,000)	30,231,000	21,659,000
Reclassification of (gains) losses on derivatives to earnings, net	12,868,000	(24,714,000)	(154,000)
Commodity Derivatives Propane [Member] | Ferrellgas, L.P. [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Derivative [Line Items]
Change in value of derivative	(48,184,000)	30,231,000	21,659,000
Reclassification of (gains) losses on derivatives to earnings, net	12,868,000	(24,714,000)	(154,000)
Interest Rate Swap [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Derivative [Line Items]
Change in value of derivative	$ 0	0	866,000
Reclassification of (gains) losses on derivatives to earnings, net		395,000	2,092,000
Interest Rate Swap [Member] | Ferrellgas, L.P. [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Including Portion Attributable to Noncontrolling Interest [Member]
Derivative [Line Items]
Change in value of derivative			866,000
Reclassification of (gains) losses on derivatives to earnings, net		$ 395,000	$ 2,092,000