Stock-based Compensation - Stock options outstanding (Details) - Stock Options	3 Months Ended
	Dec. 31, 2016 $ / shares shares
Shares
Outstanding at beginning of period | shares	672,669
Granted | shares	27,110
Forfeited | shares	(1,334)
Outstanding at end of period | shares	698,445
Exercisable at end of period (shares) | shares	567,599
Vested or expected to vest in the future (shares) | shares	694,487
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 16.49
Granted (in dollars per share) | $ / shares	12.52
Forfeited (in dollars per share) | $ / shares	8.37
Outstanding at end of period (in dollars per share) | $ / shares	16.35
Exercisable at end of period (in dollars per share) | $ / shares	17.79
Vested or expected to vest in the future (in dollars per share) | $ / shares	$ 16.40