Stock-Based Compensation Plans - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2016 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Options Outstanding, Beginning balance \| shares	4,223,710
Stock Options Outstanding, Granted \| shares	200
Stock Options Outstanding, Exercised \| shares	(1,694,440)
Stock Options Outstanding, Expired \| shares	(934,879)
Stock Options Outstanding, Ending balance \| shares	1,594,591
Stock Options Outstanding, Exercisable \| shares	1,594,149
Weighted-Average Exercise Price, Outstanding, Beginning balance \| $ / shares	$ 126.65
Weighted-Average Exercise Price, Granted \| $ / shares	110.18
Weighted-Average Exercise Price, Exercised \| $ / shares	106.68
Weighted-Average Exercise Price, Expired \| $ / shares	140.75
Weighted-Average Exercise Price, Outstanding, Ending balance \| $ / shares	139.60
Weighted-Average Exercise Price, Exercisable \| $ / shares	$ 139.60
Weighted-Average Life (In Years), Outstanding, Ending balance	1 year 6 months
Weighted-Average Life (In Years), Exercisable	1 year 6 months
Aggregate Intrinsic Value, Outstanding, Ending balance \| $	$ 39,326
Aggregate Intrinsic Value, Exercisable \| $	$ 39,305

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

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