Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Numerator:
Net income	$ 51,420	$ 48,234	$ 46,330	$ 34,763	$ 46,052	$ 46,223	$ 33,488	$ 24,085	$ 180,747	$ 149,848	$ 54,525
Denominator:
Weighted average basic shares (in shares)									12,062	11,982	11,879
Dilutive effect of restricted stock and restricted stock units (in shares)									105	206	241
Weighted average diluted shares (in shares)									12,167	12,188	12,120
Earnings per share:
Basic (in dollars per share)	$ 4.26	$ 4.00	$ 3.84	$ 2.89	$ 3.84	$ 3.85	$ 2.79	$ 2.02	$ 14.98	$ 12.51	$ 4.59
Diluted (in dollars per share)	$ 4.22	$ 3.96	$ 3.81	$ 2.86	$ 3.77	$ 3.79	$ 2.75	$ 1.98	$ 14.86	$ 12.29	$ 4.50