Stock-Based Compensation - Stock Option Activity (Detail) - $ / shares	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding Options, Beginning Balance	13,158	42,288
Options Granted	0	0
Options Exercised	(13,158)	(27,942)
Options Canceled		(1,188)
Outstanding Options, Ending Balance		13,158
Weighted Average Exercise Price Per Share, Outstanding, Beginning Balance	$ 23.36	$ 20.05
Weighted Average Exercise Price Per Share, Granted	0	0
Weighted Average Exercise Price Per Share, Exercised	$ 50.37	35.73
Weighted Average Exercise Price Per Share, Canceled		17.92
Weighted Average Exercise Price Per Share, Outstanding, Ending Balance		$ 23.36

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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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(4)
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Gross 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 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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Number of share options (or share units) exercised during the current period.

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