Stock Option Plan - Schedule of Information Concerning Outstanding and Vested Stock Options (Detail) (USD $)	12 Months Ended
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number Outstanding	927,677
Number Vested	358,597
Exercise Price $11.03 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price	$ 11.03
Number Outstanding	22,816
Number Vested	22,816
Remaining Contracted Life (Years)	1 month 6 days
Exercise Price $13.66 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price	$ 13.66
Number Outstanding	106,110
Number Vested	106,110
Remaining Contracted Life (Years)	2 years 1 month 6 days
Exercise Price $16.78 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price	$ 16.78
Number Outstanding	182,411
Number Vested	138,431
Remaining Contracted Life (Years)	4 years 4 months 24 days
Exercise Price $15.73 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price	$ 15.73
Number Outstanding	241,940
Number Vested	89,240
Remaining Contracted Life (Years)	6 years 9 months 18 days
Exercise Price $30.85 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price	$ 30.85
Number Outstanding	374,400
Number Vested	2,000
Remaining Contracted Life (Years)	8 years 9 months 18 days

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The number of exercisable share options (fully vested and expected to vest) that may be converted 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

-Section 50

-Paragraph 2

-Subparagraph (e)(2)

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

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- Definition

As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be 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 (e)(1)

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

+ Details

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- Definition

As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

+ 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 (e)(1)

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

+ Details

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- Definition

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

+ 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 (e)(1)

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

+ Details

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