Chapter 11 Reorganization (Liabilites Subject to Compromise Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Debt and Accrued Interest	$ 358	$ 358
Secured Variable And Fixed Rate Indebtedness Due Through 2023 [Member]
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Debt and Accrued Interest	172	172
Effective interest rate percentage - minimum	1.00%
Effective interest rate percentage - maximum	13.00%
Debt instrument maturity year	Dec. 31, 2023
6.00% - 8.50% Special Facility Revenue Bonds Due Through 2036 [Member]
Debt Instrument [Line Items]
Liabilities Subject to Compromise, Debt and Accrued Interest	$ 186	$ 186
Percentage of debt instrument interest rate - minimum	6.00%
Percentage of debt instrument interest rate - maximum	8.50%
Debt instrument maturity year	Dec. 31, 2036

When presenting a range of interest rates, the highest effective rate for funds borrowed under the debt agreement as of the balance sheet date.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

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When presenting a range of interest rates, the lowest effective rate for funds borrowed under the debt agreement as of the balance sheet date.

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When presenting a range of interest rates, the highest stated (contractual) rate for funds borrowed under the debt agreement as of the balance sheet date.

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- Definition

When presenting a range of interest rates, the lowest stated (contractual) rate for funds borrowed under the debt agreement as of the balance sheet date.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Latest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

The amount of debt and related accrued interest included in liabilities subject to compromise.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 852

-SubTopic 10

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6916575&loc=d3e55717-112764

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 852

-SubTopic 10

-Section 55

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6585303&loc=d3e56145-112766

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 90-7

-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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 852

-SubTopic 10

-Section 50

-Paragraph 2

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-URI http://asc.fasb.org/extlink&oid=6918054&loc=d3e56015-112765

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