Stockholders' Equity - Schedule of Additional Information Regarding Stock Appreciation Rights (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of stock appreciation rights vested (based on remeasurement-date fair value)	$ 7,000	$ 11,800	$ 6,200
Stock appreciation rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of stock appreciation rights exercised	7,024	1,090
Fair value of stock appreciation rights vested (based on remeasurement-date fair value)	$ 6,834	$ 9,955	$ 4,307
Weighted-average grant-date fair value per share of stock appreciation rights granted			$ 14.33
Weighted-average remeasurement-date fair value per share of stock appreciation rights			$ 32.94

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Exercised In Period Intrinsic Value

No definition available.

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- Definition

Weighted average fair value at remeasurement date for nonvested equity-based awards other than a stock or unit option plan remeasured during the period.

+ References

No definition available.

+ Details

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target 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)(2)(iii)(1)

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

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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

+ 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 (d)(2)

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

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