Stock-based Compensation - Stock Options Outstanding (Details) - Stock Options	3 Months Ended	9 Months Ended
	Jun. 30, 2018 $ / shares shares	Jun. 30, 2018 $ / shares shares
Shares
Outstanding at beginning of period (shares) | shares	550,259	593,753
Granted (shares) | shares	0	23,680
Exercised (shares) | shares	(6,525)	(8,191)
Expired (shares) | shares	(5,000)	(61,967)
Forfeited (shares) | shares	(7,012)	(15,553)
Outstanding at end of period (shares) | shares	531,722	531,722
Exercisable at end of period (shares) | shares	475,672	475,672
Vested or expected to vest in the future (shares) | shares	531,722	531,722
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 14.18	$ 14.76
Granted (in dollars per share) | $ / shares	0.00	20.46
Exercised (in dollars per share) | $ / shares	7.51	7.52
Expired (in dollars per share) | $ / shares	18.00	23.19
Forfeited (in dollars per share) | $ / shares	11.68	10.46
Outstanding at end of period (in dollars per share) | $ / shares	14.26	14.26
Exercisable at end of period (in dollars per share) | $ / shares	14.06	14.06
Vested or expected to vest in the future (in dollars per share) | $ / shares	$ 14.26	$ 14.26