Schedule I Parent Only Balance Sheets, Statements Of Earnings And Cash Flows (Balance Sheets) (Details) - USD ($) $ in Thousands	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
ASSETS
Cash and cash equivalents	$ 5,760	$ 4,965	$ 7,652	$ 8,289
Prepaid expenses and other current assets	33,388	39,973
Other assets, net	74,057	87,223
Total assets	1,609,969	1,683,306
LIABILITIES AND PARTNERS' CAPITAL (DEFICIT)
Other current liabilities	126,224	128,958
Long-term debt	1,995,795	1,941,335
Partners' capital (deficit)
Common unitholders	(701,188)	(570,754)
General partner unitholder	(66,991)	(65,835)
Accumulated other comprehensive income (loss)	14,601	(10,468)
Total Ferrellgas Partners, L.P. partners' capital (deficit)	(753,578)	(647,057)
Total liabilities and partners' capital (deficit)	1,609,969	1,683,306
Parent Company [Member]
ASSETS
Cash and cash equivalents	59	75	$ 2,052	$ 6
Prepaid expenses and other current assets	4	18
Total assets	63	93
LIABILITIES AND PARTNERS' CAPITAL (DEFICIT)
Other current liabilities	4,250	2,006
Long-term debt	346,525	180,454
Partners' capital (deficit)
Common unitholders	(701,188)	(570,754)
General partner unitholder	(66,991)	(65,835)
Accumulated other comprehensive income (loss)	14,601	(10,468)
Total Ferrellgas Partners, L.P. partners' capital (deficit)	(753,578)	(647,057)
Total liabilities and partners' capital (deficit)	63	93
Equity Method Investment, Summarized Financial Information, Liabilities	$ 402,866	$ 464,690