Aggregate percentage of stock based awards to me matured.

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- Definition

Starting period of vesting of share based award.

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No definition available.

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- Definition

Amount of increase in additional paid in capital (APIC) resulting from a tax benefit associated with share-based compensation plan other than an employee stock ownership plan (ESOP). Includes, but is not limited to, excess tax benefit.

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- Definition

Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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- Definition

Amount of cost to be recognized for option under share-based payment arrangement.

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- Definition

Amount of noncash expense for award of restricted stock or unit under share-based payment arrangement.

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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).

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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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- 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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No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

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

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- Definition

Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Stock Compensation - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to nonvested stock options granted	$ 0	$ 0	$ 0	$ 0
Shares, granted (in shares)	0	0
Compensation expense restricted stock awards	$ 275,000	$ 272,000	$ 867,000	949,000
Vested, shares (in shares)			25,940
Weighted average grant (in dollars per share)			$ 25.27
Fair value of shares vesting during period	101,000	9,000	$ 1,328,000	1,471,000
Performance Based Restricted Stock Awards \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, granted (in shares)			16,681		15,657	7,109
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to nonvested restricted stock	911,000		$ 911,000		$ 775,000
Income tax benefit related to share based compensation	58,000	$ 57,000	182,000	$ 199,000
Restricted Stock Units (RSUs) \| Vested Immediately
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense restricted stock awards	$ 0		$ 350,000
Key Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Starting period of vesting of stock based award			1 year
Aggregate percentage of stock based awards to be matured			100.00%
Key Employees \| Vesting in year two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock incentive plan, vesting per year			25.00%
Key Employees \| Vesting in year three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock incentive plan, vesting per year			20.00%
Independent Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Starting period of vesting of stock based award			1 year
Aggregate percentage of stock based awards to be matured			100.00%
Independent Directors \| Vesting in year one
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock incentive plan, vesting per year			33.33%
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested, shares (in shares)			13,850
Weighted average grant (in dollars per share)			$ 25.27