Subsequent Events Subsequent Events (Narrative) (Details) - USD ($) $ in Millions	May 14, 2018	May 04, 2018	Apr. 30, 2018	Jul. 31, 2017
Letters of Credit Outstanding, Amount			$ 111.8	$ 139.2
Subsequent Event [Member] | Secured Debt [Member]
Letters of Credit Outstanding, Amount		$ 100.0
Cash		75.0
Ferrellgas, L.P. [Member]
Letters of Credit Outstanding, Amount			111.8	$ 139.2
Ferrellgas, L.P. [Member] | Subsequent Event [Member] | Secured Debt [Member]
Letters of Credit Outstanding, Amount		100.0
Cash		75.0
Two Thousand and Twenty Three Credit Facility [Member] | Subsequent Event [Member] | Secured Debt [Member]
Line of Credit Facility, Maximum Borrowing Capacity		575.0
Debt Instrument, Face Amount		$ 275.0
Debt Instrument, Basis Spread on Variable Rate		5.75%
Two Thousand and Twenty Three Credit Facility [Member] | Ferrellgas, L.P. [Member] | Subsequent Event [Member] | Secured Debt [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 575.0
Debt Instrument, Face Amount		$ 275.0
Debt Instrument, Basis Spread on Variable Rate		5.75%
Two Thousand and Eighteen Credit Facility [Member] | Secured Debt [Member]
Line of Credit Facility, Maximum Borrowing Capacity			575.0
Two Thousand and Eighteen Credit Facility [Member] | Ferrellgas, L.P. [Member] | Secured Debt [Member]
Line of Credit Facility, Maximum Borrowing Capacity			575.0
Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 300.0
Revolving Credit Facility [Member] | Ferrellgas, L.P. [Member] | Subsequent Event [Member]
Line of Credit Facility, Maximum Borrowing Capacity		300.0
Letter of Credit [Member] | Subsequent Event [Member]
Line of Credit Facility, Maximum Borrowing Capacity		125.0
Letter of Credit [Member] | Ferrellgas, L.P. [Member] | Subsequent Event [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 125.0
Asset-backed Securities, Securitized Loans and Receivables [Member]
Accounts Receivable Securitization Program, Maximum Capacity			225.0
Asset-backed Securities, Securitized Loans and Receivables [Member] | Subsequent Event [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 50.0
Debt Instrument, Basis Spread on Variable Rate	2.00%
Accounts Receivable Securitization Program, Maximum Capacity	$ 250.0
Asset-backed Securities, Securitized Loans and Receivables [Member] | Ferrellgas, L.P. [Member]
Accounts Receivable Securitization Program, Maximum Capacity			$ 225.0
Asset-backed Securities, Securitized Loans and Receivables [Member] | Ferrellgas, L.P. [Member] | Subsequent Event [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 50.0
Debt Instrument, Basis Spread on Variable Rate	2.00%
Accounts Receivable Securitization Program, Maximum Capacity	$ 250.0