Revolving Credit Facility - Additional Information (Detail) - Revolving Credit Facility [Member] |
12 Months Ended |
|---|---|
|
Sep. 30, 2017
USD ($)
| |
| Line Of Credit Facility [Line Items] | |
| Revolving credit facility amount | $ 30,000,000 |
| Credit facility fee percentage | 0.15% |
| Line of credit facility expiration date | Nov. 01, 2019 |
| Borrowings outstanding | $ 0 |
| Minimum [Member] | |
| Line Of Credit Facility [Line Items] | |
| Credit facility interest rate | 1.00% |
| Maximum [Member] | |
| Line Of Credit Facility [Line Items] | |
| Credit facility interest rate | 1.75% |
| Multi-currency Overdraft Facility [Member] | Ireland | |
| Line Of Credit Facility [Line Items] | |
| Line of credit facility additional borrowing capacity | $ 5,000,000 |
| Credit facility incremental of additional borrowings | 5,000,000 |
| Multi-currency Overdraft Facility [Member] | Maximum [Member] | Ireland | |
| Line Of Credit Facility [Line Items] | |
| Line of credit facility additional borrowing capacity | $ 20,000,000 |