Disposition (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2012
Dispositions [Line Items]
Dividend of subsidiary	$ 290
Retained Earnings
Dispositions [Line Items]
Dividend of subsidiary	347
Accumulated Other Comprehensive Income (Loss)
Dispositions [Line Items]
Dividend of subsidiary	$ (57)

Equity impact of dividends to be paid-in-kind declared for common shareholders by an entity during the period. This element includes paid and unpaid dividends declared during the period.

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=6959260&loc=d3e187085-122770

Name:	us-gaap_DividendsCommonStockPaidinkind
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration