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Net Periodic Benefit Cost for Period Reconciliation of Changes in Plan Assets Projected Benefit Obligations and Amounts Recognized in Other Comprehensive Income and Accumulated Other Comprehensive Income (Detail) - Frozen Defined Benefit Pension Plans - USD ($) $ in Thousands | 12 Months Ended
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Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2019
Net Periodic Pension Cost in Income Statement |  |  |  |
Net Periodic Pension Cost in Income Statement, Interest cost | $ 1,560 | $ 1,541 | $ 1,875 |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration] | Interest Revenue (Expense), Net | Interest Revenue (Expense), Net | Interest Revenue (Expense), Net |
Net Periodic Pension Cost in Income Statement, Actual return on plan assets | $ (13,658) | $ (678) | $ (6,538) |
Net Periodic Pension Cost in Income Statement, Investment and other expenses | (507) | (377) | (539) |
Net Periodic Pension Cost in Income Statement, Difference between actual and expected return on plan assets | (15,200) | (1,386) |  | $ 4,268
Net Periodic Pension Cost in Income Statement, Anticipated expenses |  | 345 | 334 |
Net Periodic Pension Cost in Income Statement, Amortization of unrecognized net actuarial loss | 896 | 937 | 1,617 |
Net Periodic Pension Cost in Income Statement, Annual cost/change | 407 | 382 | 1,017 |
Fair Value of Pension Plan Assets |  |  |  |
Fair Value of Pension Plan Assets, Beginning Balance | 65,337 | 69,088 | 66,838 |
Fair Value of Pension Plan Assets, Actual return on plan assets | (13,658) | 678 | 6,538 |
Fair Value of Pension Plan Assets, Benefit payments | (4,225) | (4,429) | (4,288) |
Fair Value of Pension Plan Assets, Annual cost/change | (17,883) | (3,751) | 2,250 |
Fair Value of Pension Plan Assets, Ending Balance | 47,454 | 65,337 | 69,088 | 66,838
Projected Benefit Obligation |  |  |  |
Projected Benefit Obligation, Beginning balance | (61,294) | (65,398) | (65,007) |
Projected Benefit Obligation, Interest cost | (1,560) | 1,541 | (1,875) |
Projected Benefit Obligation, Benefit payments | 4,225 | 4,429 | 4,288 |
Projected Benefit Obligation, Investment and other expenses | 507 | 377 | 539 |
Projected Benefit Obligation , Anticipated expenses |  | 345 | 334 |
Projected Benefit Obligation, Actuarial (loss) gain | 13,869 | 1,184 | (3,009) |
Projected Benefit Obligation, Annual cost/change | 17,041 | 4,104 | (391) |
Projected Benefit Obligation, Ending balance | (44,253) | (61,294) | (65,398) | (65,007)
Funded status at the end of the year | 3,201 | 4,043 | 3,690 |
Other Comprehensive (Income) / Loss |  |  |  |
Other Comprehensive (Income) / Loss, Difference between actual and expected return on plan assets | 15,200 | 1,386 |  | (4,268)
Other Comprehensive (Income) / Loss, Actuarial loss (gain) | (13,869) | 1,184 | (3,009) |
Other Comprehensive (Income) / Loss, Amortization of unrecognized net actuarial loss | (896) | (937) | (1,617) |
Other Comprehensive (Income) / Loss, Annual cost/change | 435 | (735) | (2,876) |
Gross Pension Related Accumulated Other Comprehensive Income |  |  |  |
Gross Pension Related Accumulated Other Comprehensive Income, Beginning Balance | 11,493 | 12,228 | 15,104 |
Other Comprehensive (Income) / Loss, Annual cost/change | 435 | (735) | (2,876) |
Gross Pension Related Accumulated Other Comprehensive Income, Ending Balance | $ 11,928 | $ 11,493 | $ 12,228 | $ 15,104

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