Debt - Principal and Interest Payments on Debt (Detail) $ in Thousands	Sep. 30, 2018 USD ($)
Debt Disclosure [Abstract]
2019, Principal	$ 7,857
2020, Principal	8,571
2021, Principal	8,572
2022, Principal	5,000
Total, Principal	30,000
2018, Interest	689
2019, Interest	2,470
2020, Interest	1,689
2021, Interest	891
2022, Interest	2,554
Total, Interest	8,293
2018, Total	689
2019, Total	10,327
2020, Total	10,260
2021, Total	9,463
2022, Total	7,554
Total	$ 38,293