Business Combinations - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Net income	$ 6,652	$ 5,615
Basic net income per common share (in dollars per share)	$ 0.80	$ 0.68
Diluted net income per common share (in dollars per share)	$ 0.78	$ 0.66