Share-based Compensation Arrangement by Share-based Payment Award, Award Required Holding Period

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Share-based Compensation Arrangement by Share-based Payment Award, Offering Period

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Share-based Compensation Arrangement by Share-based Payment Award, Percent of Awards Issued Expected to Vest

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Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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The per share amount of a dividend declared, but not paid, as of the financial reporting date.

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Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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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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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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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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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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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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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 maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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Number of options outstanding, including both vested and non-vested options.

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Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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Value of stock (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of stock value of such awards forfeited. Stock issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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Amount of stock repurchase plan authorized.

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Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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Stockholders' Equity - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jul. 25, 2018	Feb. 28, 2018	Dec. 31, 2017	Dec. 31, 2016	May 16, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock authorized (shares)	75,000,000		75,000,000
Common stock par value (usd per share)	$ 0.0001		$ 0.0001
Preferred stock authorized (shares)	25,000,000		25,000,000
Preferred stock par value (usd per share)	$ 0.0001		$ 0.0001
Options outstanding (shares)	0		0				0
Common stock outstanding (shares)	19,472,249		19,472,249				20,135,514
Preferred stock outstanding (shares)	0		0				0
Stock repurchase authority						$ 10,000,000.0
Expected vesting percent								50.00%
Amount spent to repurchase common stock			$ 9,467,000
Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend rate (usd per share)					$ 0.125
Dividends declared					$ 2,400,000
2012 Equity Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (shares)									2,194,986
2012 Equity Plan \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			1 year
2012 Equity Plan \| Restricted Stock and Restricted Stock Units with Contingent Performance Requirements
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
2012 Equity Plan \| Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
Performance-based RSUs \| Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instruments other than options, nonvested (shares)	718,630		718,630				393,084
Granted (shares)			334,035
2011 Long Term Incentive Plan \| Restricted Stock and Restricted Stock Units with Contingent Performance Requirements
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instruments other than options, nonvested (shares)	362,974		362,974
2011 Long Term Incentive Plan \| Restricted Stock and Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized, share-based awards other than options	$ 5,900,000		$ 5,900,000
Weighted-average period over which cost is expected to be recognized			1 year 10 months 10 days
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (shares)	250,000		250,000
Award required holding period			2 years
Stock purchased during period (shares)	11,581	8,983	11,581	8,393
Stock purchased during period, value	$ 100,000		$ 100,000
Maximum \| ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Offering period, maximum			6 months