Stock Plans - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock-based compensation plans	3
Excess tax benefit from Share-based Compensation	$ 15,000	$ 1,412,000	$ 79,000
Stock compensation plan, weighted average grant date fair value of options granted	$ 0	$ 40.38	$ 40.64
Stock compensation plan, total intrinsic values of options exercised	0	3,100,000	0
Stock compensation plan, total intrinsic values of options outstanding	4,600,000
Stock compensation plan, total intrinsic values of options exercisable	1,500,000
Stock-based compensation expense	1,586,000	1,482,000	1,047,000
Stock-based compensation expense, total tax benefit recognized	555,000	516,000	359,000
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,586,000	1,482,000	1,047,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation plan, stock awards vested	633,000	559,000	481,000
Stock compensation plan, number of restricted stock units outstanding	10,500	13,500
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation plan, conversion ratio of a restricted stock unit to ordinary shares of stock	1
Stock compensation plan, restricted stock units conversion period	5 years
Stock compensation plan, number of restricted stock units outstanding	12,904	11,996
Non Employee Director \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation plan, stock awards vested	8,000	22,000	8,000
Stock compensation plan, number of restricted stock units outstanding	389
Stock compensation plan, total intrinsic value of unvested restricted stock	3,938,000
2006 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation plan, number of common stock shares reserved	200,000
Stock compensation plan, remaining number of common stock shares reserved	58,242
2006 Equity Incentive Plan \| Non Employee Director \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation plan, stock awards vested	$ 120,000	$ 120,000	$ 120,000
Deferred Compensation Plan \| Non Employee Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation plan, number of common stock shares reserved	2,500
Stock compensation plan, remained shares of common stock reserved for issuance	1,626
Director Stock Purchase Plan \| Non Employee Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation plan, number of common stock shares reserved	2,500
Stock compensation plan, remaining number of common stock shares reserved	1,126

Number Of Stock Based Compensation Plans

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Share based Compensation Arrangement by Share based Payment Award, Equity Instruments Other than Options, Nonvested, Total Intrinsic Value

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- Definition

Share Based Compensation Conversion Ratio of Equity Instruments Other Than Option to Ordinary Shares

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Aggregate number of common shares reserved for future issuance.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.29)

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Amount of cash inflow from 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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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 20

-Section 55

-Paragraph 24

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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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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

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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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-Publisher FASB

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-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(i)-(ii)

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- Definition

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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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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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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- Definition

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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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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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.

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

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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