Stock-Based Compensation - Stock Option Activity (Detail) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Shares, Beginning balance	428,258	447,359	875,498
Number of Shares, Granted	0	0	0
Number of Shares, Exercised	0	(3,452)	(3,629)
Number of Shares, Cancelled (forfeited and expired)	(125,529)	(15,649)	(424,510)
Number of Shares, Ending balance	302,729	428,258	447,359	875,498
Weighted-Average Exercise Price, Beginning balance	$ 19.97	$ 19.59	$ 20.13
Number of Shares, Exercisable	302,729
Weighted-Average Exercise Price, Granted	$ 0	$ 0	$ 0
Number of Shares, Vested and expected to vest	302,729
Weighted-Average Exercise Price, Exercised		$ 1.00	$ 1.00
Weighted-Average Exercise Price, Cancelled (forfeited and expired)	$ 24.30	$ 13.06	$ 20.86
Weighted-Average Exercise Price, Ending balance	$ 18.18	$ 19.97	$ 19.59	$ 20.13
Aggregate Intrinsic Value, Beginning balance		$ 2,175
Weighted-Average Exercise Price, Exercisable	$ 18.18
Aggregate Intrinsic Value, Exercised		2,214	4,319
Weighted-Average Exercise Price, Vested and expected to vest	$ 18.18
Aggregate Intrinsic Value, Ending balance			2,175
Weighted-Average Remaining Contractual Term, Outstanding	3 years 3 months 18 days	4 years 3 months 18 days	5 years 1 month 6 days	5 years 6 months
Aggregate Intrinsic Value, Exercisable	0
Weighted-Average Remaining Contractual Term, Exercisable	3 years 3 months 18 days
Aggregate Intrinsic Value, Vested and expected to vest	$ 0
Weighted-Average Remaining Contractual Term, Vested and expected to vest	3 years 3 months 18 days

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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.

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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.

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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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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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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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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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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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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.

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As of the balance sheet date, the weighted-average exercise price for outstanding 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 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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