Share-Based Compensation - Certain Information Related to Stock Options and Restricted Stock (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Options Number of Options beginning balance	4,125
Stock Options Number of Options Granted	230
Stock Options Number of Options Forfeited	(50)
Stock Options Number of Options Exercised	(1,900)
Stock Options Number of Options ending balance	2,405
Stock Options Number of Options Exercisable	962
Stock Options Weighted Average Exercise Price per Share Outstanding beginning balance	$ 5.56
Stock Options Weighted Average Exercise Price per Share Granted	$ 15.81
Stock Options Weighted Average Exercise Price per Share Forfeited	$ 4.51
Stock Options Weighted Average Exercise Price per Share Exercised	$ 4.93
Stock Options Weighted Average Exercise Price per Share Outstanding ending balance	$ 6.99
Stock Options Weighted Average Exercise Price per Share Exercisable	$ 4.93
Stock Options Aggregate Intrinsic Value Outstanding	$ 32,362
Stock Options Aggregate Intrinsic Value Exercisable	$ 14,926
Stock Options Weighted Average Remaining Term	3 years 10 months 17 days
Exercisable Stock Options Weighted Average Remaining Term	3 years 7 days
Restricted Stock Number of Shares beginning balance	1,600
Restricted Stock Number of Shares Granted	950
Restricted Stock Number of Shares Vested	(1,875)
Restricted Stock Number of Shares ending balance	675
Restricted Stock Weighted Average Grant Date Fair Value per Share beginning balance	$ 4.94
Restricted Stock Weighted Average Grant Date Fair Value per Share Granted	$ 12.88
Restricted Stock Weighted Average Grant Date Fair Value per Share Vested	$ 6.28
Restricted Stock Weighted Average Grant Date Fair Value per Share ending balance	$ 12.40

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The number of grants made 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).

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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).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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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.

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

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No definition available.

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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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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of fully vested and expected to vest options that are exercisable.

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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.

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As of the balance sheet date, the weighted-average exercise price (at which grantees can acquire the shares reserved for issuance) for exercisable stock options that are fully vested or expected to vest.

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Weighted average remaining contractual term for fully vested and expected to vest options that are 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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Amount by which the current fair value of the underlying stock exceeds the exercise price of fully vested and expected to vest options outstanding.

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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.

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

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No definition available.

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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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