Stock-Based Compensation - Summary of Stock Based Compensation Activity for Non-Qualified Stock Option Award (Detail) (Non-Qualified Stock Option Award [Member], USD $)	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012
Non-Qualified Stock Option Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation, Shares Outstanding, beginning balance	60,000	50,000
Stock based compensation, Shares, Granted	51,000	10,000
Stock based compensation, Shares, Exercised	(16,500)
Stock based compensation, Shares, Forfeited/Expired
Stock based compensation, Shares Outstanding, ending balance	94,500	60,000
Stock based compensation, Shares, Exercisable	19,800	16,666
Stock based compensation, Weighted Average Fair Value Per Share, beginning balance	$ 28.97	$ 28.90
Stock based compensation, Weighted Average Fair Value Per Share, Granted	$ 34.95	$ 29.34
Stock based compensation, Weighted Average Fair Value Per Share, Exercised	$ 28.90
Stock based compensation, Weighted Average Fair Value Per Share, Forfeited/Expired
Stock based compensation, Weighted Average Fair Value Per Share, ending balance	$ 32.21	$ 28.97
Stock based compensation, Weighted Average Fair Value Per Share, Exercisable	$ 28.97	$ 28.90
Stock based compensation, Weighted Average Remaining Contractual Term, Outstanding	5 years 9 months 4 days
Stock based compensation, Weighted Average Remaining Contractual Term, Exercisable	7 years 8 months 12 days	8 years 7 months 6 days
Stock based compensation, Aggregate Intrinsic Value, Outstanding	$ 385,405
Stock based compensation, Aggregate Intrinsic Value, Exercisable	$ 144,870	$ 35,167

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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.

+ References

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- Definition

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(iii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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- Definition

Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(iv)(3)-(4)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

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

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No definition available.

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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.

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-Publisher FASB

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-Paragraph 2

-Subparagraph (d)(1)

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- Definition

Weighted average grant-date fair value of non-vested options forfeited.

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No definition available.

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Weighted average grant-date fair value of non-vested options outstanding.

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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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- Definition

Number of options outstanding, including both vested and non-vested options.

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-Name Accounting Standards Codification

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Weighted average grant-date fair value of options vested.

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- Definition

Number of share options (or share units) exercised during the current period.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

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