v3.8.0.1

Share-Based Compensation - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	$ 4,700,000	$ 6,300,000	$ 8,000,000
Shares subject to stock options, granted	0	0	0
Shares subject to stock options, expired	38,525
Shares subject to stock options, outstanding	0
Number of stock options exercised	0	0	0
Current fiscal year employer matching contribution description	We make a matching contribution equal to 100% of each pre-tax dollar contributed by the participant on the first 3% of eligible compensation and 50% on the next 2% of eligible compensation
Contributions to employee benefit plan	$ 333,000	$ 338,000	$ 404,000
Primary [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Employer matching contribution, percentage	100.00%
Secondary [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Employer matching contribution, percentage	50.00%
Nonvested Shares [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares grant	2,343,522	1,318,229	1,278,329
Average grant date fair value	$ 5,600,000	$ 2,500,000	$ 6,200,000
Unrecognized compensation expense related to nonvested shares	$ 4,000,000
Nonvested outstanding weighted average remaining service period	2 years
Cash Settled Performance Shares [Member] | General and Administrative Expenses [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	$ 800,000	1,300,000
Cash Settled Performance Shares [Member] | Current Liability [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, liability	1,600,000
Cash Settled Performance Shares [Member] | Non-Current Liability [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, liability	500,000
Non-Employee Director [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense	$ 449,000	$ 214,000	$ 735,000
Executive Officers [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Service period	3 years
Executive Officers [Member] | Nonvested Shares [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional shares grant	1,492,652	550,272	724,249
Additional share grant fair value	$ 3,600,000	$ 300,000	$ 4,500,000
Executive Officers [Member] | Cash Settled Performance Shares [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of share awards		1,100,543
Fair market value of shares subject to performance conditions		$ 1,000,000
Service period		2 years
Fair market value of shares		$ 1,000,000
Executive Officers [Member] | Cash Settled Performance Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair market value of shares subject to performance conditions	$ 2,400,000
Subsequent restricted share award	774,590
Fair market value of shares	$ 2,400,000
Executive Officers [Member] | Restricted Shares Total Shareholder Return Performance Stock Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair market value of shares subject to performance conditions	$ 800,000
Subsequent restricted share award	387,295
Fair market value of shares	$ 800,000
2007 Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
The maximum number of common stock	6,125,000

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Maximum number of shares of common stock which may be delivered under the plan.

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The aggregate fair market value of the shares subject to performance conditions.

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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.

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Aggregate carrying value as of the balance sheet date of the liabilities for deferred compensation arrangements payable after one year (or the normal operating cycle, if longer). Represents currently earned compensation under cash arrangements (such as a profit-sharing plan, rabbi trust, and employee contract--excluding equity-based arrangements) that is not actually paid until a later date.

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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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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, 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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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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Number of share options (or share units) exercised during the current period.

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