Derivatives (Details) - Foreign currency forward contracts - Designated as hedging instrument - Fair value hedge instruments |
3 Months Ended | |
|---|---|---|
|
Oct. 31, 2016
USD ($)
contract
|
Oct. 31, 2015
USD ($)
|
|
| Derivatives | ||
| Term of contracts | 1 month | |
| Number of contracts | contract | 8 | |
| Aggregate value of contracts | $ 10,500,000 | |
| Term of renewed contracts | 1 month | |
| Net currency conversion losses, net of tax | $ 50,000 | $ 92,000 |