Stockholders' Equity and Stock-Based Compensation Plans - Summary of Transactions of the Company's Stock Option Plans (Detail) (Stock Options Plan [Member], USD $)	6 Months Ended
Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, Number of Options, Beginning balance	1,001,241
Exercised, Number of Options	(286,390)
Forfeited, Number of Options	(9,500)
Outstanding, Number of Options, Ending balance	777,040
Outstanding, Weighted Average Exercise Price, Beginning balance	$ 6.27
Exercised, Weighted Average Exercise Price	$ 2.43
Forfeited, Weighted Average Exercise Price	$ 15.97
Outstanding, Weighted Average Exercise Price, Ending balance	$ 8.16
Discount [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Number of Options	49,528
Granted, Weighted Average Exercise Price	$ 0.00
Granted, Weighted Average Grant-Date Fair Value	$ 32.39
Market Value [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Number of Options	22,161
Granted, Weighted Average Exercise Price	$ 41.27
Granted, Weighted Average Grant-Date Fair Value	$ 16.09

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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.

+ 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)

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

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

+ References

No definition available.

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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.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

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-Paragraph 2

-Subparagraph (d)(1)

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- Definition

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

+ References

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- Definition

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

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- Definition

Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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

+ References

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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