Share-Based Compensation Plans (Summary of Stock Option Activity) (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
Jun. 30, 2014
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Beginning Balance, Number outstanding	1,270
Exercised during 2014, Number outstanding	(391)
Ending Balance, Number outstanding	879
Vested and expected to vest at June 30, 2014, Number outstanding	879
Exercisable at June 30, 2014, Number outstanding	746
Beginning Balance, Weighted-average exercise price	$ 18.03
Exercised during 2014, Weighted-average exercise price	$ 14.15
Ending Balance, Weighted-average exercise price	$ 19.76
Vested and expected to vest at June 30, 2014, Weighted-average exercise price	$ 19.76
Exercisable at June 30, 2014, Weighted-average exercise price	$ 18.36
Ending Balance, Weighted-average remaining contractual term, years	2 years 4 months 24 days
Vested and expected to vest at June 30, 2014, Weighted-average remaining contractual term, years	2 years 4 months 24 days
Exercisable at June 30, 2014, Weighted-average remaining contractual term, years	1 year 1 month 6 days
Ending Balance, Aggregate intrinsic value	$ 7,057
Vested and expected to vest at June 30, 2014, Aggregate intrinsic value	7,057
Exercisable at June 30, 2014, Aggregate intrinsic value	$ 7,039

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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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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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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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 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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Amount by which the current fair value of the underlying stock exceeds the exercise price of fully vested and expected to vest options outstanding.

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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