v2.4.0.6

Share-Based Compensation - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
The maximum number of common stock	2,100,000
Maximum term of stock option	10 years
Share-based compensation expense	$ 7,500,000	$ 4,700,000	$ 2,600,000
Intrinsic value of the options exercised	7,000,000	1,100,000	608,000
Tax benefit recognized related to the stock option exercises	0	358,000	141,000
Subsequent Restricted Share Award	183,673
Fair market value of shares on grant date	4,500,000
Service period	4 years
Nonvested Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares grant	316,279	256,317	568,142
Average grant date fair value	10,400,000	8,100,000	4,300,000
Unrecognized compensation expense related to nonvested shares	10,300,000
Nonvested outstanding weighted average remaining service period	3 years
Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	535,000	420,000	381,000
Executive Officers [Member] | Nonvested Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares grant	129,890	204,000	400,000
Additional share grant fair value	$ 4,800,000	$ 6,500,000	$ 2,700,000

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- Definition

Maximum Number Of Shares Of Common Stock Which May Be Delivered Pursuant To Performance Based Awards

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- Definition

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Additional Grants In Period

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- Definition

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

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- Definition

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Grant Date Fair Market Value

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- Definition

Net number of share options or share units granted during the period

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No definition available.

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- Definition

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.

+ References

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- Definition

As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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- Definition

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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- Definition

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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- Definition

The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

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- Definition

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

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- Definition

Value of stock issued during the period as a result of the exercise of stock options, net of any related income tax benefit or expense recognized by the entity.

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