v2.3.0.11

Risk Management Activities (Location and Fair Value of Derivative Instruments on Condensed Consolidated Balance Sheets) (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Total Asset Derivatives	$ 306.6	$ 399.8
Total Liability Derivatives	262.8	355.5
Designated as Hedging Instruments [Member] | Interest Rate Risk Activities [Member]
Total Asset Derivatives	60.7	61.1
Designated as Hedging Instruments [Member] | Interest Rate Risk Activities [Member] | Price Risk Management Assets (Noncurrent) [Member]
Total Asset Derivatives	60.7	61.1
Designated as Hedging Instruments [Member] | Commodity Price Risk Programs [Member]
Total Liability Derivatives	0.6	1.2
Designated as Hedging Instruments [Member] | Commodity Price Risk Programs [Member] | Price Risk Management Liabilities (Current) [Member]
Total Liability Derivatives	0.5	1.0
Designated as Hedging Instruments [Member] | Commodity Price Risk Programs [Member] | Price Risk Management Liabilities (Noncurrent) [Member]
Total Liability Derivatives	0.1	0.2
Not Designated as Hedging Instruments [Member] | Commodity Price Risk Programs [Member]
Total Asset Derivatives	245.9	338.7
Total Liability Derivatives	262.2	354.3
Not Designated as Hedging Instruments [Member] | Commodity Price Risk Programs [Member] | Price Risk Management Assets (Current) [Member]
Total Asset Derivatives	116.0	159.5
Not Designated as Hedging Instruments [Member] | Commodity Price Risk Programs [Member] | Price Risk Management Assets (Noncurrent) [Member]
Total Asset Derivatives	129.9	179.2
Not Designated as Hedging Instruments [Member] | Commodity Price Risk Programs [Member] | Price Risk Management Liabilities (Current) [Member]
Total Liability Derivatives	134.5	172.9
Not Designated as Hedging Instruments [Member] | Commodity Price Risk Programs [Member] | Price Risk Management Liabilities (Noncurrent) [Member]
Total Liability Derivatives	$ 127.7	$ 181.4

X

- Definition

Fair value of derivative asset, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624163-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44C
-Subparagraph a
-Clause 1
-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 133
-Paragraph 205G
-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.

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Fair value of derivative liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624163-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44C
-Subparagraph a
-Clause 1
-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 133
-Paragraph 205G
-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.

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeLiability
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant