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

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-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

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

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Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

+ References

Reference 1: 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=6959260&loc=d3e187085-122770

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-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

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-Publisher SEC

-Name Regulation S-X (SX)

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-Name Accounting Standards Codification

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The amount authorized by an entity's Board of Directors under a stock repurchase plan.

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The remaining repurchase amount authorized by an entity's Board of Directors under a stock repurchase plan.

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Stockholders' equity (Details Textual) (USD $) In Billions, except Share data in Millions, unless otherwise specified	1 Months Ended							3 Months Ended		9 Months Ended		1 Months Ended
	Oct. 10, 2012	Sep. 07, 2012	Jul. 19, 2012	Jun. 07, 2012	Mar. 15, 2012	Mar. 07, 2012	Dec. 15, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 07, 2012 Dividend to be paid [Member]
Common stock, dividends declared per share	$ 0.36		$ 0.36		$ 0.36		$ 0.36
Dividends paid per share		$ 0.36		$ 0.36		$ 0.36		$ 0.36000000	$ 0.28000000	$ 1.08000000	$ 0.28000000	$ 0.36
Amount available for stock repurchases under a board approved stock repurchase plan										$ 1.6
Stock Repurchase Program, Authorized Amount										$ 10
Common stock issued								8.7		20.6