Stock-based Compensation - Stock Options Outstanding (Details) - Stock Options	3 Months Ended	6 Months Ended
	Mar. 31, 2017 $ / shares shares	Mar. 31, 2017 $ / shares shares
Shares
Outstanding at beginning of period (shares) | shares	698,445	672,669
Granted (shares) | shares	2,300	29,410
Forfeited (shares) | shares	(12,570)	(13,904)
Outstanding at end of period (shares) | shares	688,175	688,175
Exercisable at end of period (shares) | shares	563,943	563,943
Vested or expected to vest in the future (shares) | shares	684,250	684,250
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 16.35	$ 16.49
Granted (in dollars per share) | $ / shares	12.24	12.50
Forfeited (in dollars per share) | $ / shares	13.39	12.91
Outstanding at end of period (in dollars per share) | $ / shares	16.39	16.39
Exercisable at end of period (in dollars per share) | $ / shares	17.82	17.82
Vested or expected to vest in the future (in dollars per share) | $ / shares	$ 16.44	$ 16.44