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Share-Based Compensation Plans - Additional Information (Detail) - $ / shares | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Stock Options |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Stock options awarded | 0 | 0 | 0 | 0
Unvested stock options forfeited | 0 | 0 | 0 | 0
Restricted Stock | Key Employees |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Number of shares granted | 0 | 0 | 0 | 36,180
Weighted average fair value per share |  |  |  | $ 35.82
Shares vested |  |  |  | 9,063
Stock options, vested and expected to vest |  | 27,117 |  | 27,117
Restricted Stock | Key Employees | Share-based Payment Arrangement, Tranche 1 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Percentage of shares vested on each anniversary of the grant date |  |  |  | 16.50%
Vesting date |  |  |  | Jan. 01, 2020
Restricted Stock | Key Employees | Share-based Compensation Award, Tranche 2 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Percentage of shares vested on each anniversary of the grant date |  |  |  | 16.50%
Vesting date |  |  |  | Jan. 01, 2021
Restricted Stock | Key Employees | Share-based Compensation Award, Tranche 3 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Percentage of shares vested on each anniversary of the grant date |  |  |  | 17.00%
Vesting date |  |  |  | Jan. 01, 2022
Restricted Stock | Key Employees | Vesting Schedule Two |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Percentage of shares vested on each anniversary of the grant date |  |  |  | 100.00%
Vesting date |  |  |  | Mar. 15, 2022
Percentage of stock award subject to vesting |  |  |  | 50.00%
Restricted Stock | Non Employee Director |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Number of shares granted | 29,893 | 19,275 | 81,502 | 50,661
Weighted average fair value per share | $ 22.58 | $ 24.97 | $ 24.85 | $ 28.50
Restricted Stock Units | Key Employees |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Number of shares granted | 0 | 0 | 161,238 | 175,498
Weighted average fair value per share |  |  | $ 30.32 | $ 30.18
Shares vested |  |  | 3,375 |
Vesting year |  |  | 3 years |
Restricted Stock Units | Key Employees | Share-based Payment Arrangement, Tranche 1 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Percentage of shares vested on each anniversary of the grant date |  |  | 10.00% | 10.00%
Vesting date |  |  | Jun. 18, 2021 | Jun. 18, 2021
Restricted Stock Units | Key Employees | Share-based Compensation Award, Tranche 2 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Percentage of shares vested on each anniversary of the grant date |  |  | 20.00% | 20.00%
Vesting date |  |  | Jun. 18, 2022 | Jun. 18, 2022
Restricted Stock Units | Key Employees | Share-based Compensation Award, Tranche 3 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Percentage of shares vested on each anniversary of the grant date |  |  | 30.00% | 30.00%
Vesting date |  |  | Jun. 18, 2023 | Jun. 18, 2023
Restricted Stock Units | Key Employees | Vesting Schedule Two |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Stock options, vested and expected to vest | 90,906 |  | 90,906 |
Percentage of shares vested on each anniversary of the grant date |  |  | 100.00% |
Vesting date |  |  | Mar. 15, 2023 |
Percentage of stock award subject to vesting |  |  | 50.00% |
Restricted Stock Units | Key Employees | Vesting Schedule One |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Stock options, vested and expected to vest | 66,957 |  | 66,957 |
Restricted Stock Units | Key Employees | Share-based Compensation Award, Tranche 4 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Percentage of shares vested on each anniversary of the grant date |  |  | 40.00% | 40.00%
Vesting date |  |  | Jun. 18, 2024 | Jun. 18, 2024
Restricted Stock Units | Key Employees | Share-based Payment Arrangement, Tranche 5 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Percentage of shares vested on each anniversary of the grant date |  |  | 16.50% |
Vesting date |  |  | Jan. 01, 2021 |
Restricted Stock Units | Key Employees | Share-based Compensation Award, Tranche 6 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Percentage of shares vested on each anniversary of the grant date |  |  | 16.50% |
Vesting date |  |  | Jan. 01, 2022 |
Restricted Stock Units | Key Employees | Share-based Compensation Award, Tranche 7 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Percentage of shares vested on each anniversary of the grant date |  |  | 17.00% |
Vesting date |  |  | Jan. 01, 2023 |
Restricted Stock Units | Non Employee Director |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Number of shares granted | 41,667 |  | 41,667 |
Vesting year |  |  | 3 years |
Restricted Stock Units | Non Employee Director | Share-based Payment Arrangement, Tranche 1 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Vesting date |  |  | Jan. 01, 2022 |
Restricted Stock Units | Non Employee Director | Share-based Compensation Award, Tranche 2 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Vesting date |  |  | Jan. 01, 2023 |
Restricted Stock Units | Non Employee Director | Share-based Compensation Award, Tranche 3 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Vesting date |  |  | Jan. 01, 2024 |

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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 The weighted average fair value at grant date for nonvested equity-based awards issued 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 The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period. + 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)(2) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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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. + References No definition available. + Details
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- Definition Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur. + 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 (e)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Percentage of vesting of award 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 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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