Revolving Credit Facility - Additional Information (Detail) - Revolving Credit Facility [Member] - USD ($)	Nov. 02, 2016	Nov. 04, 2013	Sep. 30, 2016
Line Of Credit Facility [Line Items]
Credit facility initiation date		Nov. 04, 2013
Revolving credit facility amount		$ 20,000,000
Borrowings under credit facility			$ 0
Line of credit facility, expiration period		3 years
Debt outstanding			$ 0
Subsequent Event [Member]
Line Of Credit Facility [Line Items]
Revolving credit facility amount	$ 30,000,000
Line of credit facility, expiration period	3 years
Credit facility fee percentage	0.15%
Minimum [Member] | Subsequent Event [Member]
Line Of Credit Facility [Line Items]
Credit facility interest rate	1.00%
Maximum [Member] | Subsequent Event [Member]
Line Of Credit Facility [Line Items]
Credit facility interest rate	1.75%
Multi-currency Overdraft Facility [Member] | Ireland | Subsequent Event [Member]
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 | Subsequent Event [Member]
Line Of Credit Facility [Line Items]
Line of credit facility additional borrowing capacity	$ 20,000,000