Supplemental Cash Flow Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Changes in Assets and Liabilities, Exclusive of Changes Shown Separately
Accounts receivable, net	$ 24	$ (62)	$ 0
Inventories	7	(53)	(71)
Recoverable pension and postretirement costs	106	(436)	(26)
Accrued pension liability - affiliates	137	271	(27)
Accounts payable	(64)	41	47
Income taxes payable/receivable	114	54	(77)
Accrued postretirement liability - affiliates	(221)	157	3
Regulatory assets	125	(18)	(77)
Other assets	108	(80)	(54)
Other liabilities	(78)	(15)	29
Total Changes in Assets and Liabilities, Exclusive of Changes Shown Separately	$ 258	$ (141)	$ (253)

Increase Decrease in Recoverable Pension and Postretirement Costs

No definition available.

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- Definition

The increase (decrease) during the reporting period in the aggregate amount of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

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

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- Definition

The increase (decrease) during the reporting period in amount due within one year (or one business cycle) from customers for the credit sale of goods and services.

+ References

+ Details

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- Definition

The increase (decrease) during the period in the amount due for taxes based on the reporting entity's earnings or attributable to the entity's income earning process (business presence) within a given jurisdiction.

+ References

+ Details

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- Definition

The increase (decrease) during the reporting period in the aggregate value of all inventory held by the reporting entity, associated with underlying transactions that are classified as operating activities.

+ References

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- Definition

The increase (decrease) during the reporting period of all assets and liabilities used in operating activities.

+ References

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- Definition

The increase (decrease) during the reporting period in other assets used in operating activities not separately disclosed in the statement of cash flows. May include changes in other current assets, other noncurrent assets, or a combination of other current and noncurrent assets.

+ References

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- Definition

The increase (decrease) during the reporting period in other liabilities used in operating activities not separately disclosed in the statement of cash flows. May include changes in other current liabilities, other noncurrent liabilities, or a combination of other current and noncurrent liabilities.

+ References

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- Definition

The increase (decrease) during the reporting period in the amount due to fund non-pension benefits provided to former, retired, and disabled employees.

+ References

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- Definition

The increase (decrease) during the reporting period in prepaid pension costs.

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- Definition

The increase (decrease) during the reporting period in the value of assets that are created when regulatory agencies permits public utilities to defer costs (revenues) to the balance sheet. This element is a the increase (decrease) of regulatory assets and liabilities combined.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

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

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