Defined Benefit Pension Plan - Fair Value Estimates (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Defined benefit pension plan
Fair values	$ 15,902	$ 18,382	$ 16,332
Total
Defined benefit pension plan
Fair values	15,902	18,382
Level 1
Defined benefit pension plan
Fair values	469	122
Level 2
Defined benefit pension plan
Fair values	15,433	18,260
Level 3
Defined benefit pension plan
Fair values	0	0
Government bonds | Total
Defined benefit pension plan
Fair values	9,280
Government bonds | Level 1
Defined benefit pension plan
Fair values	0
Government bonds | Level 2
Defined benefit pension plan
Fair values	9,280
Government bonds | Level 3
Defined benefit pension plan
Fair values	0
Equity securities | Total
Defined benefit pension plan
Fair values		10,977
Equity securities | Level 1
Defined benefit pension plan
Fair values		0
Equity securities | Level 2
Defined benefit pension plan
Fair values		10,977
Equity securities | Level 3
Defined benefit pension plan
Fair values		0
Corporate bonds | Total
Defined benefit pension plan
Fair values	4,611	5,453
Corporate bonds | Level 1
Defined benefit pension plan
Fair values	0	0
Corporate bonds | Level 2
Defined benefit pension plan
Fair values	4,611	5,453
Corporate bonds | Level 3
Defined benefit pension plan
Fair values	0	0
Diversified fund | Total
Defined benefit pension plan
Fair values	1,542	1,830
Diversified fund | Level 1
Defined benefit pension plan
Fair values	0	0
Diversified fund | Level 2
Defined benefit pension plan
Fair values	1,542	1,830
Diversified fund | Level 3
Defined benefit pension plan
Fair values	0	0
Cash | Total
Defined benefit pension plan
Fair values	469	122
Cash | Level 1
Defined benefit pension plan
Fair values	469	122
Cash | Level 2
Defined benefit pension plan
Fair values	0	0
Cash | Level 3
Defined benefit pension plan
Fair values	$ 0	$ 0