Capital Transactions (Details 2) (USD $) In Millions, except Per Share data, unless otherwise specified	1 Months Ended	4 Months Ended	5 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
Feb. 08, 2013	Feb. 12, 2012	Feb. 09, 2011	Feb. 10, 2010	May 16, 2012	Jun. 01, 2012	Jun. 30, 2011	Jun. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share Repurchase Program
Dividends per common share (in dollars per share)	$ 0.19	$ 0.18	$ 0.165	$ 0.15							$ 0.18	$ 0.165	$ 0.15
Cash dividend payment					$ 201	$ 3	$ 192	$ 187	$ 2	$ 2	$ 204	$ 194	$ 189

The cash outflow from the distribution of an entity's earnings in the form of dividends to common shareholders.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3291-108585

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 18

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 20

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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