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Stock-Based Compensation - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Restricted Stock Units (RSU) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
The vesting graded scale	Over a three, four, and five-year period, or in certain instances the RSUs were issued with five year cliff vesting.
Performance Share Awards (PSAs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cumulative performance targets	3 years
Grants under performance share awards	95,691	181,670
Stock Only Stock Appreciation Rights (SOSARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock	3 years
Vesting term	10 years

X

- Definition

Share based compensation arrangement by share based payment award award vesting period description.

+ References

No definition available.

+ Details

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X

- Definition

Share based compensation arrangement by share based payment award equity instruments other than options cumulative performance target period.

+ References

No definition available.

+ Details

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X

- Definition

Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ 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 (a)(1)

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

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X

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ 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 (a)(1)

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

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target 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)(2)(iii)(1)

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

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