Stock Option Activity (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012
Shares
Outstanding as of the beginning of the period	1,029	1,560
Exercised		(3)
Forfeited/expired/cancelled	(98)	(522)
Outstanding at the end of the period	931	1,035
Options exercisable at September 30, 2013	931	1,035
Aggregate intrinsic value of options exercised during the period
Weighted Average Exercise Price
Outstanding as of the beginning of the period	$ 29.04	$ 24.10
Exercised		$ 9.11
Forfeited/expired/cancelled	$ 23.17	$ 14.63
Outstanding at the end of the period	$ 29.66	$ 29.01
Options exercisable at September 30, 2013	$ 29.66	$ 29.01

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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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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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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.

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

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

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