Stock-Based Compensation - Stock Option Activity (Detail) - USD ($)	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding Options, Beginning Balance	13,158	42,288	241,276
Options Granted	0	0	0
Options Exercised	(13,158)	(27,942)	(186,968)
Options Canceled		(1,188)	(12,020)
Outstanding Options, Ending Balance	0	13,158	42,288
Weighted Average Exercise Price Per Share, Outstanding, Beginning Balance	$ 23.36	$ 20.05	$ 20.19
Options Vested	0
Weighted Average Exercise Price Per Share, Granted	$ 0	0	0
Options Exercisable	0
Weighted Average Exercise Price Per Share, Exercised	$ 50.37	35.73	24.92
Weighted Average Exercise Price Per Share, Canceled		17.92	18.16
Weighted Average Exercise Price Per Share, Outstanding, Ending Balance		$ 23.36	$ 20.05
Weighted Average Exercise Price Per Share, Vested	0
Weighted Average Exercise Price Per Share, Exercisable	$ 0
Weighted Average Remaining Contractual Life, Outstanding	0 years
Weighted Average Remaining Contractual Life, Vested	0 years
Weighted Average Remaining Contractual Life, Exercisable	0 years
Aggregate Intrinsic Value, Outstanding	$ 0
Aggregate Intrinsic Value, Vested	0
Aggregate Intrinsic Value, Exercisable	$ 0

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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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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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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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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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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 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 of the plan that expired.

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

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