Stock-Based Compensation - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of shares of the Company's common stock	2,985,000
Shares available to be issued under stock-based incentive plan	1,191,000
Options granted, vesting conditions	Most options granted since 2005 contain performance-based vesting conditions
Options granted	0	0	0
Unrecognized compensation cost related to nonvested share	$ 0
Outstanding restricted shares	323,151
Compensation expense	2,058,000us-gaap_RestrictedStockExpense	1,041,000us-gaap_RestrictedStockExpense	947,000us-gaap_RestrictedStockExpense
Stock-based compensation expense related to stock options	0us-gaap_StockOptionPlanExpense	0us-gaap_StockOptionPlanExpense	97,000us-gaap_StockOptionPlanExpense
Stock based compensation grants	0	0	0
Unearned compensation related to restricted stock	1,568,000	2,129,000	1,608,000
Restricted stock weighted average period	2 years
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Income tax benefit related to options	861,000	152,000	170,000
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Income tax benefit related to options	$ 49,000	$ 0	$ 1,000
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted	5 years
Minimum [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted	3 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted	10 years
Maximum [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted	5 years

Share based compensation arrangement by share based payment award award vesting terms description.

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- Definition

Share based compensation arrangement by share based payment award options and restricted stock shares outstanding number.

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- Definition

Unearned stock based compensation expense.

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- Definition

The maximum number of shares authorized for issuance under the deferred compensation arrangement as of the balance sheet date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

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Number of shares issued pursuant to the terms of a deferred compensation arrangement.

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- Definition

Unrecognized cost of unvested share-based compensation awards.

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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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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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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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-Publisher FASB

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- Definition

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

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- Definition

Value, after forfeitures, of stock or other type of equity granted of any equity-based compensation plan other than an employee stock ownership plan (ESOP).

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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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