Share-Based Compensation - Certain Information Regarding Company's Share-Based Compensation (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense, Total	$ 1,761	$ 680	$ 2,928	$ 1,692
Deferred tax benefits, Total	206	206	492	540
Realized tax benefits, Total	1,690	128	2,124	432
Excess tax (benefits) shortfall from stock-based compensation	155	71	4	(71)
Weighted average fair value per option or share, Restricted stock grants	$ 4.88		$ 4.88
Intrinsic value of options exercised	4,381	332	4,537	367
Cash received for strike price and tax withholdings				518
Shares acquired through cashless exercise	1,284	147	1,683	147
Value of shares acquired through cashless exercise	8,443	583	10,295	583
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense, Stock options	309	309	613	646
Deferred tax benefits, Total	119	119	236	249
Realized tax benefits, Total	1,690	128	1,750	141
Excess tax (benefits) shortfall from stock-based compensation	155	71	63	71
Weighted average fair value per option or share, Stock option grants			$ 0.37
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense, Restricted Stock	1,452	371	2,315	1,046
Deferred tax benefits, Total	87	87	256	291
Realized tax benefits, Total			374	291
Excess tax (benefits) shortfall from stock-based compensation			(59)	(142)
Weighted average fair value per option or share, Restricted stock grants	$ 4.88		$ 4.88
Fair value of restricted stock vested			$ 2,548	$ 1,164

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

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

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-Name Accounting Standards Codification

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

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- Definition

Amount of deferred income tax expense (benefit) and income tax credits.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

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- Definition

Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

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-Publisher FASB

-Name Accounting Standards Codification

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- Definition

Amount of cash outflow for realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

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- Definition

The noncash expense that represents the cost of restricted stock or unit distributed to employees as compensation.

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- Definition

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).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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- Definition

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

+ References

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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- Definition

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

+ References

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- Definition

Cash received for strike price and tax withholdings.

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- Definition

Shares acquired through cashless exercise.

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- Definition

Value of shares acquired.

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