Retirement Benefit Obligations - Additional Information (Detail) - USD ($) $ in Millions |
6 Months Ended | |
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Jun. 30, 2026 |
Jun. 30, 2025 |
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| Defined Benefit Plan Disclosure [Line Items] | ||
| Defined benefit plan, assumed health care cost trend rate, description | The health care cost trend rate used to determine benefit plan costs for 2026 for pre-65 retirees is 8.05%, with an ultimate rate of 4.50% in 2034, and for post-65 retirees, the health care cost trend rate is 7.15%, with an ultimate rate of 4.50% in 2034. The health care cost trend rate used to determine benefit plan costs for 2025 for pre-65 retirees was 8.50%, with an ultimate rate of 4.50% in 2034, and for post-65 retirees, the health care cost trend rate was 7.50%, with an ultimate rate of 4.50% in 2034. | |
| Supplemental Employee Retirement Plans, Defined Benefit | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Benefit payments under SERP Plan | $ 0.3 | |
| Expected additional benefit payments for the remainder of 2020 | $ 0.4 | |
| Pre-65 retirees | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Health care cost trend rate, assumed | 8.05% | 8.50% |
| Health care cost trend rate, ultimate rate | 4.50% | 4.50% |
| Health care cost trend rate, ultimate rate in year | 2034 | 2034 |
| Post-65 retirees | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Health care cost trend rate, assumed | 7.15% | 7.50% |
| Health care cost trend rate, ultimate rate | 4.50% | 4.50% |
| Health care cost trend rate, ultimate rate in year | 2034 | 2034 |
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- Definition Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Description of direction and pattern of change in assumed health care cost trend rate used to measure expected cost of benefits for defined benefit postretirement plan. No definition available.
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of benefit for defined benefit plan expected to be paid in remainder of current fiscal year. No definition available.
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- Definition Assumed rate, for next fiscal year, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Ultimate trend rate for health care cost for defined benefit postretirement plan. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Year ultimate health care cost trend rate is expected to be reached, in YYYY format. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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