Stock-Based Compensation and Stock Awards - Schedule of Option Activity (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding at December 31, 2013, Number of Options	512,895
Granted, Number of Options	0
Exercised, Number of Options	(48,523)
Forfeited, Number of Options	(5,125)
Outstanding at December 31,2014, Number of Options	459,247
Exercisable at December 31,2014, Number of Options	417,123
Outstanding at December 31, 2013, Weighted Average Price	$ 56.25
Granted, Weighted Average Price	$ 0
Exercised, Weighted Average Price	$ 58.74
Forfeited, Weighted Average Price	$ 68.18
Outstanding at December 31,2014, Weighted Average Price	$ 55.86
Exercisable at December 31,2014, Weighted Average Price	$ 54.59
Outstanding at December 31,2014, Aggregate intrinsic value	$ 9.6
Exercisable at December 31,2014, Aggregate intrinsic value	$ 9.2
Outstanding at December 31,2014, Weighted Average Remaining Contractual Life (in years)	5 years 2 months 12 days
Exercisable at December 31,2014, Weighted Average Remaining Contractual Life (in years)	5 years

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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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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

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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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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.

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

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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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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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