Stock-Based Compensation - Stock Option Activity (Detail) - $ / shares	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Options Outstanding, Beginning Balance	500,000
Stock Options, Granted	0	0	0
Stock Options, Exercised	(300,000)
Stock Options, Forfeited, Canceled or Expired	0
Stock Options Outstanding, Ending Balance	200,000	500,000
Stock Options, Exercisable	200,000
Stock Options Outstanding, Weighted Average Exercise Price Per Share, Beginning Balance	$ 48.41
Stock Options, Granted Weighted Average Exercise Price Per Share	0
Stock Options, Exercised Weighted Average Exercise Price Per Share	50.78
Stock Options, Forfeited, Canceled or Expired Weighted Average Exercise Price Per Share	0
Stock Options Outstanding, Weighted Average Exercise Price Per Share, Ending Balance	0	$ 48.41
Stock Options, Exercisable Weighted Average Exercise Price Per Share	$ 42.89

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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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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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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- Definition

For presentations that combine terminations, 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 or that expired.

+ References

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Weighted average price of options that were either forfeited or expired.

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

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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 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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