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

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

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

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

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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

-Publisher FASB

-Name Accounting Standards Codification

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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

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

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

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

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Stock Plans and Other Incentives - Summary of Options (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding	582,500	627,724	645,448	663,172
Remaining Contractual Life (Years)	3 years 10 months 24 days	4 years 6 months
Weighted Average Exercise Price	$ 9.52	$ 9.05	$ 8.94	$ 8.82
Intrinsic Value	$ 9,695,750	$ 6,392,016
Exercise Price Range $4.09 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices	$ 4.09
Outstanding		17,724
Remaining Contractual Life (Years)		8 months 12 days
Weighted Average Exercise Price		$ 4.09
Intrinsic Value		268,341
Exercise Price Range $7.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices	$ 7.50
Outstanding	47,500	70,000
Remaining Contractual Life (Years)	2 years 7 months 6 days	3 years 7 months 6 days
Weighted Average Exercise Price	$ 7.50	$ 7.50
Intrinsic Value	886,825	821,100
Exercise Price Range $8.03 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices	$ 8.03
Outstanding	225,000	225,000
Remaining Contractual Life (Years)	5 years 7 months 6 days	6 years 7 months 6 days
Weighted Average Exercise Price	$ 8.03	$ 8.03
Intrinsic Value	4,082,625	2,521,125
Exercise Price Range $10.40 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices	$ 10.40
Outstanding	290,000	315,000
Remaining Contractual Life (Years)	2 years 4 months 24 days	3 years 4 months 24 days
Weighted Average Exercise Price	$ 10.40	$ 10.40
Intrinsic Value	4,573,300	2,781,450
Exercise Price Range $18.52 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices	$ 18.52
Outstanding	20,000
Remaining Contractual Life (Years)	9 years 4 months 24 days
Weighted Average Exercise Price	$ 18.52
Intrinsic Value	$ 153,000