Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 14.F)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 14
-Section F

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Unrecognized cost of unvested share-based compensation awards.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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- 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.

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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 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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- Definition

Description of pertinent provisions of equity-based compensation awards that have actual or potential impact upon the company's financial statements.

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- Definition

Period For Achieving Performance Target

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Share based compensation arrangement by share based payment award equity instruments other than options earned in period.

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Share based compensation arrangement by Share based payment award percentage of shares issued and outstanding as of the balance sheet date.

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- Definition

Share based compensation arrangement by share based payment award performance stock award vesting period.

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Share based compensation awards number of shares allowed to be issued.

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Stock Based Compensation [Line Items]

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Stock Compensation Plans - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock Based Compensation [Line Items]
Compensation expense	$ 4,871	$ 5,650	$ 3,250
Officer [Member]
Stock Based Compensation [Line Items]
Vesting period of stock awards	4 years
One Year Performance Targets Based Shares [Member]
Stock Based Compensation [Line Items]
Performance stock vesting period	4 years
Three Year Performance Targets Based Shares [Member]
Stock Based Compensation [Line Items]
Performance stock vesting period	3 years
Earned Shares [Member]
Stock Based Compensation [Line Items]
Total unvested shares	58,000
Unearned Shares [Member]
Stock Based Compensation [Line Items]
Total unvested shares	112,000
2009 Equity Incentive Plan [Member]
Stock Based Compensation [Line Items]
Number of shares allowed to be issued	6,161,000
Percentage of Shares issued and outstanding	15.40%
Performance Shares [Member]
Stock Based Compensation [Line Items]
Number of shares to be earned from awards granted	0
Compensation expense	$ 589	$ 2,479	$ 1,083
Unamortized future compensation expense	$ 1,581
Performance-based restricted stock awards, performance targets description	Performance-based restricted stock awards granted to executive officers in 2016 were subject to achievement of one-year and three year performance targets established by the Board of Directors. Earned shares related to one-year performance targets vest annually over four years. Earned shares related to three-year targets vest upon completion of the three-year period.
Number of shares to be earned from awards granted	0	110,000	152,000
Total unvested shares	170,000	366,000
Performance Shares [Member] \| Minimum [Member]
Stock Based Compensation [Line Items]
Performance period	1 year
Performance Shares [Member] \| Maximum [Member]
Stock Based Compensation [Line Items]
Performance period	3 years
Restricted Stock [Member]
Stock Based Compensation [Line Items]
Compensation expense	$ 2,177	$ 1,356	$ 1,316
Unamortized future compensation expense	$ 3,454