Stock Based Compensation - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized under Stock Incentive Plans	3,600,000
Common Stock, Capital shares reserved for future issuance	4,900,000
Shares available under Stock Incentive Plans	3,500,000
Matching contributions in 401(k) / profit sharing plan	$ 387	$ 300	$ 284
Restricted stock and unit awards to employees	319,055
Unrecognized compensation related to unvested restricted stock and unit awards	5,079
Amortization related to restricted stock and unit awards	7,605	6,202	8,559
Amortization capitalized in development activities	41	34	21
Weighted average period of unrecognized compensation expected to be recognized	9 months 15 days
Long-Term Incentive Program \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Percentage		0.00%
Long-Term Incentive Program \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Percentage		100.00%
Director \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock and unit awards to employees	19,250
Unrecognized compensation related to unvested restricted stock and unit awards	350
Vesting period of restricted stock	1 year
Management \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock and unit awards to employees	299,805	284,461	565,137
Unrecognized compensation related to unvested restricted stock and unit awards	5,413	4,719	7,065
Vesting period of restricted stock	3 years
Compensation expense recognized at date of grant	1,451	1,008	3,649
Management \| Long-Term Incentive Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock and unit awards to employees		718,960
Unrecognized compensation related to unvested restricted stock and unit awards		$ 5,411

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 number of common shares reserved for future issuance.

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The amount of payment into the fund established for purposes of making future disbursements to the individual in accordance with the terms and understanding of the deferred compensation arrangement.

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

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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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Additional share-based compensation cost recognized as a result of an occurrence of an event that accelerates its recognition.

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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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Percentage of vesting of share-based compensation awards.

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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 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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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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