Common Stock Repurchases - Additional Information (Detail) (Stock Repurchase Plan Two, USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended	1 Months Ended
Oct. 31, 2013	Oct. 31, 2013	Oct. 31, 2012	Dec. 08, 2011 Maximum
Stockholders Equity Note [Line Items]
Amount authorized for repurchase of Company's common stock				$ 30
Repurchase of common stock (in shares)	296,045	46,638	56,324
Repurchase of common stock	$ 20.1	$ 3.7	$ 3.9
Average purchase price of common stock	$ 67.98	$ 79.97	$ 69.86

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Number of shares that have been repurchased and retired during the period.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

+ Details

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- Definition

Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

+ References

+ Details

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- Definition

Amount of a stock repurchase plan authorized by an entity's Board of Directors.

+ References

No definition available.

+ Details

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- Definition

Total cost of shares repurchased divided by the total number of shares repurchased.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

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