Basis of Presentation and Nature of Operations Cash Flow Adjustment (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2012 Cash flow revision	Jun. 30, 2012 Cash flow revision	Sep. 30, 2012 Cash flow revision	Dec. 31, 2012 Cash flow revision	Dec. 31, 2011 Cash flow revision
Net cash provided by (used for) operating activities	$ 1,424	$ 315	$ (15)	$ (29)	$ (44)	$ (57)	$ (53)
Net cash provided by (used for) financing activities	$ 545	$ 991	$ 15	$ 29	$ 44	$ 57	$ 53

Amount of net cash from (used in) the entity's continuing operations, excluding cash flows derived by the entity from its discontinued operations.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-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 26

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 24

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3521-108585

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 26

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

Name:	us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration