Stock-Based Compensation - Summary of Stock Options (Detail) (Stock Options [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding shares, beginning of year	9,674
Granted, shares	2,099
Exercised, shares	(2,798)
Forfeited or expired, shares	(597)
Outstanding shares, end of year	8,378
Exercisable shares, end of year	4,451
Outstanding, Weighted Average Exercise Price, beginning of year	$ 35.98
Granted, Weighted Average Exercise Price	$ 41.23
Exercised, Weighted Average Exercise Price	$ 35.85
Forfeited or expired, Weighted Average Exercise Price	$ 37.60
Outstanding, Weighted Average Exercise Price, end of year	$ 37.22
Exercisable, Weighted Average Exercise Price, end of year	$ 36.05

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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.

+ References

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)(iii)

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- Definition

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.

+ References

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- Definition

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.

+ References

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)-(4)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-SubTopic 10

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-Subparagraph (c)(1)(iv)(3)-(4)

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- Definition

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

+ References

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- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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- Definition

Weighted average price at which option holders acquired shares when converting their stock options into shares.

+ References

No definition available.

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- Definition

Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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