CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning Balance (in shares) at Sep. 30, 2017		33,724,000
Beginning Balance at Sep. 30, 2017	$ 61,408	$ 34	$ 78,677	$ (17,450)	$ 147
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		187,000
Exercise of stock options	495		495
Settlement of restricted stock units (in shares)		706,000
Settlement of restricted stock units	0	$ 1	(1)
Acquisition-related shares issued (in shares)		3,180,000
Acquisition-related shares issued	27,487	$ 3	27,484
Stock-based compensation expense	5,927		5,927
Amortization of earnout shares	710		710
Other comprehensive income (loss)
Net loss	(9,680)			(9,680)
Foreign currency translation adjustment	(350)				(350)
Unrealized gain (loss) on investments	(28)				(28)
Other comprehensive income (loss)	(10,058)
Ending Balance (in shares) at Jun. 30, 2018		37,797,000
Ending Balance at Jun. 30, 2018	94,224	$ 38	113,292	(18,875)	(231)
Beginning Balance (in shares) at Mar. 31, 2018		35,059,000
Beginning Balance at Mar. 31, 2018	73,721	$ 35	89,109	(16,091)	668
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		114,000
Exercise of stock options	329		329
Settlement of restricted stock units (in shares)		109,000
Settlement of restricted stock units	0	$ 1	(1)
Acquisition-related shares issued (in shares)		2,515,000
Acquisition-related shares issued	21,877	$ 2	21,875
Stock-based compensation expense	1,980		1,980
Other comprehensive income (loss)
Net loss	(2,784)			(2,784)
Foreign currency translation adjustment	(942)				(942)
Unrealized gain (loss) on investments	43				43
Other comprehensive income (loss)	(3,683)
Ending Balance (in shares) at Jun. 30, 2018		37,797,000
Ending Balance at Jun. 30, 2018	$ 94,224	$ 38	113,292	(18,875)	(231)
Beginning Balance (in shares) at Sep. 30, 2018	37,961,224	37,961,000
Beginning Balance at Sep. 30, 2018	$ 95,394	$ 38	116,944	(21,002)	(586)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)	1,362,605	1,362,000
Exercise of stock options	$ 4,421	$ 1	4,420
Settlement of restricted stock units (in shares)		786,000
Settlement of restricted stock units	0	$ 1	(1)
Issuance of common stock under employee stock purchase plan (in shares)		68,000
Issuance of common stock under employee stock purchase plan	491		491
Stock-based compensation expense	7,291		7,291
Other comprehensive income (loss)
Net loss	(4,006)			(4,006)
Foreign currency translation adjustment	(1,213)				(1,213)
Unrealized gain (loss) on investments	26				26
Other comprehensive income (loss)	$ (5,193)
Ending Balance (in shares) at Jun. 30, 2019	40,177,044	40,177,000
Ending Balance at Jun. 30, 2019	$ 103,324	$ 40	129,145	(24,088)	(1,773)
Beginning Balance (in shares) at Mar. 31, 2019		39,348,000
Beginning Balance at Mar. 31, 2019	98,069	$ 39	124,613	(23,989)	(2,594)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		726,000
Exercise of stock options	2,265	$ 1	2,264
Settlement of restricted stock units (in shares)		103,000
Settlement of restricted stock units	0
Stock-based compensation expense	2,268		2,268
Other comprehensive income (loss)
Net loss	(99)			(99)
Foreign currency translation adjustment	814				814
Unrealized gain (loss) on investments	7				7
Other comprehensive income (loss)	$ 722
Ending Balance (in shares) at Jun. 30, 2019	40,177,044	40,177,000
Ending Balance at Jun. 30, 2019	$ 103,324	$ 40	$ 129,145	$ (24,088)	$ (1,773)