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Stock-Based Compensation - Schedule of Information Related to Outstanding SOSARS (Detail) (Stock Only Stock Appreciation Rights (SOSARs) [Member], USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Stock Only Stock Appreciation Rights (SOSARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance, Outstanding	1,977,133	2,121,454
Granted	281,881	361,923
Exercised	(26,245)	(435,562)
Canceled / forfeited	(29,842)	(73,901)
Ending Balance, Outstanding	2,202,927	1,973,914
Beginning Balance, Weighted Average Exercise Price, Outstanding	$ 13.91	$ 12.93
Weighted Average Exercise Price, Granted	$ 29.22	$ 18.36
Weighted Average Exercise Price, Exercised	$ 15.67	$ 12.63
Weighted Average Exercise Price, Canceled / forfeited	$ 19.36	$ 16.25
Ending Balance, Weighted Average Exercise Price, Outstanding	$ 15.77	$ 13.87
Weighted average grant date fair value per share	$ 9.81	$ 5.64
Aggregate grant date fair value	$ 2,764	$ 2,042
Black-Scholes assumptions
Dividend yield	1.48%	2.18%
Risk free rate of return	1.74%	0.99%
Volatility	37.59%	39.62%
Expected life	6 years	6 years

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Share based compensation arrangement by share based payment award options grant date fair value.

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Share based compensation arrangement by share Based payment award options grant date fair value per share.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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-Publisher FASB

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-SubTopic 10

-Section 50

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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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Weighted average expected volatility rate of share-based compensation awards.

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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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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 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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