Earnings Per Share - Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share
Net Income									$ 47,180	$ 27,545	$ 28,904
Less: distributed earnings allocated to participating securities									(18)
Less: undistributed earnings allocated to participating securities									(135)
Net income available to common shareholders									$ 47,027	$ 27,545	$ 28,904
Denominator for basic earnings per share - Weighted-average shares outstanding									9,007,814	9,189,876	9,193,235
Effect of dilutive securities stock options or awards									2,923	9,293	10,674
Denominator for diluted earnings per share									9,010,737	9,199,169	9,203,909
Basic earnings per share available to common stockholders	$ 1.53	$ 1.27	$ 1.33	$ 1.09	$ 0.81	$ 0.76	$ 0.82	$ 0.76	$ 5.22	$ 3.00	$ 3.14
Basic earnings per share available to common stockholders	$ 1.53	$ 1.27	$ 1.32	$ 1.09	$ 0.81	$ 0.76	$ 0.81	$ 0.76	$ 5.22	$ 2.99	$ 3.14