Contractual service period for vesting of stock options granted.

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Contractual term period for the expiration of stock options granted.

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Maximum number of employee for performance unit awards.

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Share based compensation arrangement by share based payment award number of additional shares available for grant.

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Number of share instruments newly issued under a share-based compensation plan.

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The vesting percentage of restricted stock over the vesting term.

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Shares reserved and unissued which are allocated to other outstanding awards.

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Aggregate number of common shares reserved for future issuance.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of cash inflow from realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

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Amount of cash outflow for realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

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Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.

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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Number of share instruments newly issued under a share-based compensation plan.

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Weighted average grant-date fair value of options vested.

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Number of shares of stock issued as of the balance sheet date, including shares that had been issued and were previously outstanding but which are now held in the treasury.

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Stock-Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Employee $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Feb. 22, 2019 shares	Feb. 22, 2018 shares	Feb. 24, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Associated cash flows from financing activities \| $			$ 500
Associated cash flows from operating activities \| $	$ 600	$ 1,700
Restricted stock vesting period	3 years
Stock-based compensation \| $	$ 5,619	5,083	4,599
Unrecognized compensation expense \| $	$ 2,800
Weighted average recognition period of compensation expenses	1 year 10 months 24 days
Total intrinsic value of options exercised \| $	$ 3,500	$ 3,500	$ 2,500
Weighted-average grant-date fair value per share of options granted \| $ / shares	$ 23.74	$ 15.49	$ 9.99
Weighted-average grant-date fair value per share of options vested \| $ / shares	$ 15.41	$ 12.26	$ 12.95
After three years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting percentage	25.00%
After four years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting percentage	25.00%
After five years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting percentage	50.00%
January 2016 - December 2018 [Member] \| Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period share issuance range				128,240
January 2015 - December 2017 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period share issuance range					49,188
January 2014 - December 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period share issuance range						30,893
Stock Option and Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation \| $	$ 2,100	$ 2,300	$ 2,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	3 years
Restricted Stock [Member] \| After three years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	3 years
Restricted Stock [Member] \| After four years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	4 years
Restricted Stock [Member] \| After five years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	5 years
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	3 years
Operating expense \| $	$ 2,400	$ 1,900	$ 1,600
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period share issuance range	128,240
Maximum [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	5 years
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period share issuance range	0
Minimum [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	3 years
Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual service	3 years
Contractual term	7 years
Shares issued to non employee director	1,363	1,942	3,279
2018 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved	1,100,000
Reserved and unissued shares	1,100,000
2018 Omnibus Incentive Plan [Member] \| Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual grant of shares	0
2011 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved	2,350,000
Additional grant under Plan	0
Restricted stock vesting period	3 years
Reserved and unissued shares	637,695	756,218
Maximum member of management and executive employees eligible for awards \| Employee	20
2011 Omnibus Incentive Plan [Member] \| Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual grant of shares	0
2011 Omnibus Incentive Plan [Member] \| Non Employee Director [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual grant of shares	12,000
2003 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved	1,236,000
Additional grant under Plan	0
Reserved and unissued shares	0	0
Directors' Deferred Fee Plan [Member] \| Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units issued in lieu of cash compensation to non employee directors	11,577	15,152	23,734