Goodwill and intangibles Goodwill and intangibles (Narrative) (Details) - USD ($) |
3 Months Ended | 6 Months Ended | |||
|---|---|---|---|---|---|
Jan. 31, 2016 |
Jul. 31, 2015 |
Jan. 31, 2015 |
Jan. 31, 2016 |
Jan. 31, 2015 |
|
| Goodwill [Line Items] | |||||
| Goodwill impairment | $ 0 | $ 0 | $ 29,316,000 | $ 0 | |
| WTI average closing price | $ 44.90 | $ 56.63 | |||
| WTI quarterly price decrease | 20.70% | ||||
| WTi crude curve decrease | 6.50% | ||||
| Ferrellgas, L.P. [Member] | |||||
| Goodwill [Line Items] | |||||
| Goodwill impairment | $ 0 | $ 0 | $ 29,316,000 | $ 0 | |
| WTI average closing price | $ 44.90 | $ 56.63 | |||
| WTI quarterly price decrease | 20.70% | ||||
| WTi crude curve decrease | 6.50% | ||||