Cash flows (Details) (USD $) In Millions	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010
Supplemental disclosures of cash flow information
Interest paid to non-affiliates	$ 50	$ 46
Income taxes paid	(21)	44
Supplemental disclosures of noncash activities
Shareholders reinvested common stock dividends in entity's common stock in noncash transactions under Dividend Reinvestment and Stock Purchase Plan (DRIP)	12	11
Noncash increases in common stock for director and officer compensatory plans	5.6	2.3
Real estate acquired in settlement of loans in noncash transactions	$ 5	$ 2

The amount of cash paid for interest of non-affiliates during the period.

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- Definition

The amount of real estate that the entity acquired in settlement of loans in noncash (or part noncash) transactions. Noncash is defined as an information about all investing and financing activities of an enterprise during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments during the period.

+ Details

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- Definition

Value of stock issued during the period from director and officer compensatory plans in noncash transactions.

+ Details

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- Details

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- Definition

The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3536-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 29
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 27
-Subparagraph f
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4297-108586

+ Details

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- Definition

Value of stock issued during the period from a dividend reinvestment plan (DRIP). A dividend reinvestment plan allows the holder of the stock to reinvest dividends paid to them by the entity on new issues of stock by the entity.

+ References

Reference 1: 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

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- Details

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