Segment Information - Summarizes Revenue by Geographic Region (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenues	$ 9,455	$ 9,817	$ 9,612	$ 9,091	$ 9,056	$ 10,556	$ 8,106	$ 8,741	$ 37,975	$ 36,459
United States
Segment Reporting Information [Line Items]
Revenues									22,686	20,396
Europe and Middle East
Segment Reporting Information [Line Items]
Revenues									4,843	7,594
Asia
Segment Reporting Information [Line Items]
Revenues									8,760	6,518
Other
Segment Reporting Information [Line Items]
Revenues									$ 1,686	$ 1,951