Net Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator
Net income	$ 7,361	$ 4,816	$ 17,019	$ 6,527
Denominator
Weighted average shares outstanding, basic (in shares)	37,323,458	37,108,486	37,278,760	37,101,968
Weighted average common equivalent shares (in shares)	172,030	143,858	134,504	145,816
Weighted average shares outstanding, diluted (in shares)	37,495,488	37,252,344	37,413,264	37,247,784
Net income per share, basic (in dollars per share)	$ 0.20	$ 0.13	$ 0.46	$ 0.18
Net income per share, diluted (in dollars per share)	$ 0.20	$ 0.13	$ 0.45	$ 0.18
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equity instruments excluded from diluted net income (loss) per share calculation as the effect would have been anti-dilutive (in shares)	936,459	699,171	891,187	483,620
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equity instruments excluded from diluted net income (loss) per share calculation as the effect would have been anti-dilutive (in shares)	129,440	129,252	99,489	111,435