CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($)	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Sep. 30, 2014	$ 23,942,000	$ 31,000	$ 59,946,000	$ (36,027,000)	$ (8,000)
Beginning Balance (in shares) at Sep. 30, 2014		30,521,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options	$ 246,000		246,000
Exercise of stock options (in shares)	232,203	232,000
Settlement of restricted stock units	$ 0
Settlement of restricted stock units (in shares)		255,000
Acquisition-related closing shares	347,000	$ 1,000	346,000
Acquisition-related closing shares (in shares)		713,000
Stock-based compensation expense	3,367,000		3,367,000
Components of other comprehensive income:
Net income	2,526,000			2,526,000
Currency translation adjustment	0
Change in unrealized gain (loss) on investments	5,000				5,000
Other comprehensive income	2,531,000
Ending Balance at Sep. 30, 2015	30,433,000	$ 32,000	63,905,000	(33,501,000)	(3,000)
Ending Balance (in shares) at Sep. 30, 2015		31,721,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options	$ 1,755,000	$ 1,000	1,754,000
Exercise of stock options (in shares)	661,663	662,000
Settlement of restricted stock units	$ 0
Settlement of restricted stock units (in shares)		262,000
Acquisition-related closing shares	0
Acquisition-related closing shares (in shares)		137,000
Stock-based compensation expense	4,079,000		4,079,000
Amortization of closing shares and earnout shares	1,298,000		1,298,000
Components of other comprehensive income:
Net income	1,959,000			1,959,000
Currency translation adjustment	(46,000)				(46,000)
Change in unrealized gain (loss) on investments	7,000				7,000
Other comprehensive income	1,920,000
Ending Balance at Sep. 30, 2016	$ 39,485,000	$ 33,000	71,036,000	(31,542,000)	(42,000)
Ending Balance (in shares) at Sep. 30, 2016	32,781,704	32,782,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options	$ 687,000		687,000
Exercise of stock options (in shares)	235,514	235,000
Settlement of restricted stock units	$ 0	$ 1,000	(1,000)
Settlement of restricted stock units (in shares)		707,000
Stock-based compensation expense	5,478,000		5,478,000
Amortization of closing shares and earnout shares	1,477,000		1,477,000
Components of other comprehensive income:
Net income	14,092,000			14,092,000
Currency translation adjustment	208,000				208,000
Change in unrealized gain (loss) on investments	(19,000)				(19,000)
Other comprehensive income	14,281,000
Ending Balance at Sep. 30, 2017	$ 61,408,000	$ 34,000	$ 78,677,000	$ (17,450,000)	$ 147,000
Ending Balance (in shares) at Sep. 30, 2017	33,724,392	33,724,000