| Comprehensive Income (Loss) [Table Text Block] |
| | | | | | | Tax | | | | |
| | | Before-Tax | | | (Expense) | | | Net-of-Tax | |
| | | Amount | | | or Benefit | | | Amount | |
| Three Months Ended June 30, 2026 | | | | | | | | | | | | |
| Interest rate swaps: | | | | | | | | | | | | |
| Unrealized gains | | $ | 506,950 | | | $ | (130,489 | ) | | $ | 376,461 | |
| Transfer of realized gains to interest expense | | | (231,048 | ) | | | 59,473 | | | | (171,575 | ) |
| Net interest rate swaps | | | 275,902 | | | | (71,016 | ) | | | 204,886 | |
| Defined benefit plans: | | | | | | | | | | | | |
| Amortization of net actuarial gains | | | (7,829 | ) | | | 2,015 | | | | (5,814 | ) |
| Other comprehensive income | | $ | 268,073 | | | $ | (69,001 | ) | | $ | 199,072 | |
| Three Months Ended June 30, 2025 | | | | | | | | | | | | |
| Interest rate swaps: | | | | | | | | | | | | |
| Unrealized losses | | $ | (20,816 | ) | | $ | 5,358 | | | $ | (15,458 | ) |
| Transfer of realized gains to interest expense | | | (323,513 | ) | | | 83,273 | | | | (240,240 | ) |
| Net interest rate swaps | | | (344,329 | ) | | | 88,631 | | | | (255,698 | ) |
| Defined benefit plans: | | | | | | | | | | | | |
| Amortization of net actuarial gains | | | (10,379 | ) | | | 2,671 | | | | (7,708 | ) |
| Other comprehensive loss | | $ | (354,708 | ) | | $ | 91,302 | | | $ | (263,406 | ) |
| | | | | | | Tax | | | | | |
| | | Before-Tax | | | (Expense) | | | Net-of-Tax | |
| | | Amount | | | or Benefit | | | Amount | |
| Nine Months Ended June 30, 2026 | | | | | | | | | | | | |
| Interest rate swaps: | | | | | | | | | | | | |
| Unrealized gains | | $ | 1,132,692 | | | $ | (291,556 | ) | | $ | 841,136 | |
| Transfer of realized gains to interest expense | | | (829,579 | ) | | | 213,535 | | | | (616,044 | ) |
| Net interest rate swaps | | | 303,113 | | | | (78,021 | ) | | | 225,092 | |
| Defined benefit plans: | | | | | | | | | | | | |
| Amortization of net actuarial gains | | | (23,487 | ) | | | 6,045 | | | | (17,442 | ) |
| Other comprehensive income | | $ | 279,626 | | | $ | (71,976 | ) | | $ | 207,650 | |
| Nine Months Ended June 30, 2025 | | | | | | | | | | | | |
| Interest rate swaps: | | | | | | | | | | | | |
| Unrealized gains | | $ | 507,492 | | | $ | (130,628 | ) | | $ | 376,864 | |
| Transfer of realized gains to interest expense | | | (1,034,976 | ) | | | 266,403 | | | | (768,573 | ) |
| Net interest rate swaps | | | (527,484 | ) | | | 135,775 | | | | (391,709 | ) |
| Defined benefit plans: | | | | | | | | | | | | |
| Amortization of net actuarial gains | | | (31,134 | ) | | | 8,013 | | | | (23,121 | ) |
| Other comprehensive loss | | $ | (558,618 | ) | | $ | 143,788 | | | $ | (414,830 | ) |
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