Share-Based Compensation Plans - Additional Information (Detail) - $ / shares	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options awarded	0	0
Unvested stock options forfeited	0	0
Restricted Stock \| Key Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted	0	36,180
Weighted average fair value per share		$ 35.82
Shares vested		9,063
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	23,127	15,842
Weighted average fair value per share	$ 29.19	$ 30.38
Restricted Stock Units \| Key Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted	94,281	0
Weighted average fair value per share	$ 29.63
Shares vested	3,375
Vesting year	3 years
Stock options, vested and expected to vest	90,906
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	16.50%
Vesting date	Jan. 01, 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	16.50%
Vesting date	Jan. 01, 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	17.00%
Vesting date	Jan. 01, 2023
Restricted Stock Units \| 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, 2023
Percentage of stock award subject to vesting	50.00%

Percentage of Stock Award Subject to Vesting

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- Definition

Share based compensation arrangement by share based payment award, award vesting date.

+ References

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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=116856206&loc=d3e5070-113901

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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=116856206&loc=d3e5070-113901

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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).

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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
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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.

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- Definition

Gross number of share options (or share units) granted during the period.

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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=116856206&loc=d3e5070-113901

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- Definition

Percentage of vesting of award under share-based payment arrangement.

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- Definition

Number of non-vested options forfeited.

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