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Stock-Based Compensation - Narrative (Detail) - shares | 9 Months Ended | 69 Months Ended
--- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Retirement eligibility target period | 1 year |  |
Restricted Stock Units (RSU) |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Percentage of awards granted | 40.00% |  |
Cumulative performance targets | 3 years |  |
Additional service period | 5 years |  |
Performance Share Awards (PSAs) |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Percentage of awards granted | 60.00% |  |
Cumulative performance targets | 2 years |  |
Additional service period | 1 year |  |
Market index period | 3 years |  |
Grants under performance share awards (in shares) | 162,480 | 171,150 |
SOSARs |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vesting term | 10 years |  |
Share-based payment award, shares issued in period (in shares) |  |  | 0

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- Definition Share based compensation arrangement by share based payment award equity instruments other than options cumulative performance target period. + References No definition available. + Details
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- Definition Share based compensation arrangement by share based payment award equity instruments other than options market index period. + References No definition available. + Details
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- Definition Share based compensation arrangement by share based payment award equity instruments other than options retirement eligibility target period. + References No definition available. + Details
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- Definition Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Number of shares issued under share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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