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
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Unrecognized cost of unvested share-based compensation awards.

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

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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

The noncash expense that accounts for the value of stock or unit options distributed to employees as compensation.

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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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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 ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Based Compensation [Line Items]
Stock Option	$ 0	$ 0	$ 0
Options outstanding	0	0
Compensation expense	$ 5,650,000	$ 3,250,000	2,587,000
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	114,000
Unearned Shares [Member]
Stock Based Compensation [Line Items]
Total unvested shares	252,000
Minimum [Member]
Stock Based Compensation [Line Items]
Vesting period of stock awards	3 years
Maximum [Member]
Stock Based Compensation [Line Items]
Vesting period of stock awards	4 years
2009 Equity Incentive Plan [Member]
Stock Based Compensation [Line Items]
Number of shares allowed to be issued	6,149,000
Percentage of Shares issued and outstanding	15.30%
Performance Shares [Member]
Stock Based Compensation [Line Items]
Number of shares to be earned from awards granted	0
Compensation expense	$ 2,479,000	$ 1,083,000	$ 600,000
Unamortized future compensation expense	$ 3,864,000
Performance-based restricted stock awards, performance targets description	Performance-based restricted stock awards granted to executive officers in 2015 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	110,000	152,000	0
Total unvested shares	366,000	316,000
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	$ 1,356,000	$ 1,316,000	$ 1,871,000
Unamortized future compensation expense	$ 5,930,000