Summary of Status of Restricted Stock Units and Changes (Detail) (Restricted Stock Units, USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restricted Stock Units
Number of Nonvested Stock Units
Nonvested at beginning period	3,921	7,018	11,164
Restricted stock units granted	1,923	1,893	1,461
Restricted stock units vested	(3,640)	(4,867)	(5,316)
Restricted stock units forfeited	(44)	(123)	(291)
Nonvested at ending period	2,160	3,921	7,018
Weighted Average Grant Date Fair Value
Nonvested at beginning period	$ 2.90	$ 2.68	$ 1.99
Restricted stock units granted	$ 5.13	$ 3.13	$ 4.55
Restricted stock units vested	$ 2.96	$ 2.60	$ 1.75
Restricted stock units forfeited	$ 4.92	$ 2.60	$ 2.47
Nonvested at ending period	$ 4.90	$ 2.90	$ 2.68
Weighted Average Remaining Recognition Period (Years)
Nonvested at ending period	3 months 22 days	5 months 5 days	9 months 29 days

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section 50

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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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 weighted average fair value at grant date for nonvested equity-based awards issued 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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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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Weighted average remaining contractual term for equity-based awards excluding options, 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 equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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