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Number of common stock repurchased under stock repurchase program.

+ References

No definition available.

+ Details

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- Definition

Aggregate dividends paid during the period for each share of common stock outstanding.

+ 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 S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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- Definition

Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

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- Definition

The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

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Stockholders' Equity - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2007	Jan. 31, 2015
Changes In Equity And Comprehensive Income Line Items [Line Items]
Repurchase authorization, shares			10,000,000
Common stock shares repurchased	925,700
Cash dividends paid to common stockholders	$ 14us-gaap_DividendsCommonStockCash	$ 13us-gaap_DividendsCommonStockCash
Cash dividend paid per share	$ 0.22	$ 0.20
Maximum [Member]
Changes In Equity And Comprehensive Income Line Items [Line Items]
Shares remaining available for repurchase under the current authorization	1,000,000
Subsequent Event [Member]
Changes In Equity And Comprehensive Income Line Items [Line Items]
Repurchase authorization, shares				5,000,000