Summarizes Stock Appreciation Rights (SARs) Activity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options outstanding, beginning balance, shares	2,129,929	2,163,825	2,132,506
Granted, shares	510,000	160,000	609,642
Exercise of Common Stock options for cash (in shares)	672,753	176,896	571,964
Forfeited	24,000	17,000	6,359
Stock options outstanding, ending balance, shares	1,943,176	2,129,929	2,163,825
Exercisable, Ending Balance	1,055,176	1,520,720	1,222,959
Stock options outstanding, beginning balance, weighted average exercise price	$ 8.82	$ 8.12	$ 6.34	$ 12.19
Granted, weighted average exercise price	$ 19.64	$ 12.88	$ 12.31
Exercised, weighted average exercise price	$ 7.21	$ 4.46	$ 5.88
Forfeited, weighted average exercise price	$ 11.27	$ 4.05	$ 5.66
Exercisable, Weighted Average Exercise Price, Ending Balance	$ 12.21	$ 7.57	$ 7.23
Outstanding, Weighted Average Remaining Contractual Term Ending Balance	6 years 11 months 27 days	6 years 11 months 27 days	6 years 8 months 27 days
Exercisable, Weighted Average Remaining Contractual Term Ending Balance	6 years 2 months 12 days	6 years 2 months 12 days	6 years 26 days
Outstanding, Aggregate Intrinsic Value, Ending Balance	$ 28,379	$ 5,640	$ 15,408
Exercisable, Aggregate Intrinsic Value, Ending Balance	19,314	5,966	9,831
Stock Appreciation Rights (SARs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options outstanding, beginning balance, shares
Granted, shares	495,000
Exercise of Common Stock options for cash (in shares)
Forfeited
Stock options outstanding, ending balance, shares	495,000
Exercisable, Ending Balance
Stock options outstanding, beginning balance, weighted average exercise price
Granted, weighted average exercise price	$ 19.19
Exercised, weighted average exercise price
Forfeited, weighted average exercise price
Exercisable, Weighted Average Exercise Price, Ending Balance
Outstanding, Weighted Average Remaining Contractual Term Ending Balance	6 years 6 months
Exercisable, Weighted Average Remaining Contractual Term Ending Balance	0 years
Outstanding, Aggregate Intrinsic Value, Ending Balance	3,770
Exercisable, Aggregate Intrinsic Value, Ending Balance

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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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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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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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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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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

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

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

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

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

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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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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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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.

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-Publisher SEC

-Name Regulation S-X (SX)

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