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Fair Value Measurements Fair Value Measurements (Fair Value Inputs, Liabilities, Quantitative Information) (Details) (USD $)
In Thousands, unless otherwise specified
 9 Months Ended
Apr. 30, 2015
Jul. 31, 2014
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value $ 100us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue $ 6,400us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
Fair Value Measurements, Valuation Techniques Discounted cash flow  
Weighted Average of Unobservable Input 20.00%fgp_WeightedAverageofUnobservableInput  
Minimum [Member]    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Range of Unobservable Inputs 5.00%fgp_RangeofUnobservableInputs
/ us-gaap_RangeAxis
= us-gaap_MinimumMember		  
Maximum [Member]    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Range of Unobservable Inputs 80.00%fgp_RangeofUnobservableInputs
/ us-gaap_RangeAxis
= us-gaap_MaximumMember		  
Ferrellgas, L.P. [Member]    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value $ 100us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
/ dei_LegalEntityAxis
= fgp_FerrellgasLPMember		 $ 6,400us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
/ dei_LegalEntityAxis
= fgp_FerrellgasLPMember
Fair Value Measurements, Valuation Techniques Discounted cash flow  
Weighted Average of Unobservable Input 20.00%fgp_WeightedAverageofUnobservableInput
/ dei_LegalEntityAxis
= fgp_FerrellgasLPMember		  
Ferrellgas, L.P. [Member] | Minimum [Member]    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Range of Unobservable Inputs 5.00%fgp_RangeofUnobservableInputs
/ dei_LegalEntityAxis
= fgp_FerrellgasLPMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember		  
Ferrellgas, L.P. [Member] | Maximum [Member]    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Range of Unobservable Inputs 80.00%fgp_RangeofUnobservableInputs
/ dei_LegalEntityAxis
= fgp_FerrellgasLPMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember