Summary and Changes in Stock Options Outstanding (Detail) - $ / shares shares in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Shares
Outstanding, Beginning Balance	5,750	5,853	6,166
Granted	1,159	1,089	771
Exercised	(1,315)	(1,135)	(904)
Canceled	(87)	(57)	(180)
Outstanding, Ending Balance	5,507	5,750	5,853
Weighted average exercise price
Outstanding, Beginning Balance	$ 9.31	$ 7.54	$ 7.62
Granted	37.21	18.41	9.24
Exercised	5.01	6.50	5.96
Canceled	46.08	56.83	25.68
Outstanding, Ending Balance	$ 15.63	$ 9.31	$ 7.54

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-SubTopic 10
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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-Publisher FASB
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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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