v2.4.0.8

Fair Value Disclosures (Fair Value Of Financial Assets And Liabilities Measured On A Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified | Jun. 30, 2013 | Dec. 31, 2012
--- | --- | ---
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Available-for-sale securities | $ 108.6 | $ 111.8
Fair value assets measured on recurring basis, total | 182.1 | 260.0
Fair value liabilities measured on recurring basis, total | 52.5 | 115.5
Physical Price Risk Programs [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Fair value assets measured on recurring basis, derivative financial instruments | 14.6 | 35.4
Fair value liabilities measured on recurring basis, total | 0 | 0
Financial Price Risk Programs [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Fair value assets measured on recurring basis, derivative financial instruments | 28.0 | 72.4
Fair value liabilities measured on recurring basis, total | 52.5 | 115.5
Interest Rate Risk Activities [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Fair value assets measured on recurring basis, derivative financial instruments | 30.9 | 40.4
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Available-for-sale securities | 22.4 | 27.4
Fair value assets measured on recurring basis, total | 50.0 | 98.9
Fair value liabilities measured on recurring basis, total | 51.3 | 115.0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Physical Price Risk Programs [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Fair value assets measured on recurring basis, derivative financial instruments | 0 | 0
Fair value liabilities measured on recurring basis, derivative financial instruments | 0 | 0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Financial Price Risk Programs [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Fair value assets measured on recurring basis, derivative financial instruments | 27.6 | 71.5
Fair value liabilities measured on recurring basis, derivative financial instruments | 51.3 | 115.0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Interest Rate Risk Activities [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Fair value assets measured on recurring basis, derivative financial instruments | 0 | 0
Significant Other Observable Inputs (Level 2) [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Available-for-sale securities | 86.2 | 84.4
Fair value assets measured on recurring basis, total | 132.1 | 161.0
Fair value liabilities measured on recurring basis, total | 0.2 | 0.5
Significant Other Observable Inputs (Level 2) [Member] | Physical Price Risk Programs [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Fair value assets measured on recurring basis, derivative financial instruments | 14.6 | 35.4
Fair value liabilities measured on recurring basis, derivative financial instruments | 0 | 0
Significant Other Observable Inputs (Level 2) [Member] | Financial Price Risk Programs [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Fair value assets measured on recurring basis, derivative financial instruments | 0.4 | 0.8
Fair value liabilities measured on recurring basis, derivative financial instruments | 0.2 | 0.5
Significant Other Observable Inputs (Level 2) [Member] | Interest Rate Risk Activities [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Fair value assets measured on recurring basis, derivative financial instruments | 30.9 | 40.4
Significant Unobservable Inputs (Level 3) [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Available-for-sale securities | 0 | 0
Fair value assets measured on recurring basis, total | 0 | 0.1
Fair value liabilities measured on recurring basis, total | 1.0 | 0
Significant Unobservable Inputs (Level 3) [Member] | Physical Price Risk Programs [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Fair value assets measured on recurring basis, derivative financial instruments | 0 | 0
Fair value liabilities measured on recurring basis, derivative financial instruments | 0 | 0
Significant Unobservable Inputs (Level 3) [Member] | Financial Price Risk Programs [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Fair value assets measured on recurring basis, derivative financial instruments | 0 | 0.1
Fair value liabilities measured on recurring basis, derivative financial instruments | 1.0 | 0
Significant Unobservable Inputs (Level 3) [Member] | Interest Rate Risk Activities [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |
Fair value assets measured on recurring basis, derivative financial instruments | $ 0 | $ 0

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- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562 + Details
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- Definition Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226008-175313 + Details
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