Share-Based Compensation - Additional Information (Detail) $ in Thousands	6 Months Ended
Jun. 30, 2017 USD ($) Anniversaries shares
2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted	0
Restricted Stock Grants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	192,000
Shares withheld for taxes	149,000
Common stock in lieu of taxes \| $	$ 9,657
Restricted Stock Grants [Member] \| 2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	188,000
Vesting period	5 years
Number of anniversaries of the vesting date following the date of grant \| Anniversaries	4
Restricted Stock Grants [Member] \| Share-based Compensation Award, Tranche One [Member] \| 2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting right percentage	20.00%
Restricted Stock Grants [Member] \| Share-based Compensation Award, Tranche Two [Member] \| 2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting right percentage	20.00%
Restricted Stock Grants [Member] \| Share-based Compensation Award, Tranche Three [Member] \| 2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting right percentage	20.00%
Restricted Stock Grants [Member] \| Share-based Compensation Award Tranche Four [Member] \| 2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting right percentage	20.00%
Restricted Stock Grants [Member] \| Share-based Compensation Award Tranche Five [Member] \| 2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting right percentage	20.00%
Restricted Stock Grants [Member] \| Non-employee [Member] \| 2017 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	4,000
Vesting period	1 year
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted	0

Number of anniversaries of grant date upon which restricted stock units vest.

No definition available.

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- Definition

The amount of adjustment to stockholders' equity associated with an employee's income tax withholding obligation as part of a net-share settlement of a share-based award.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&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://www.xbrl.org/2003/role/presentationRef
-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=96867065&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

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

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- Definition

Percentage of vesting of share-based compensation awards.

+ References

+ Details

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- Definition

For net-share settlement of share-based awards when the employer settles employees' income tax withholding obligations, this element represents the number of shares the employees use to repay the employer.

+ References

No definition available.

+ Details

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