v2.4.0.6

Derivative Instruments (Narrative) (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified | 3 Months Ended | 6 Months Ended | 0 Months Ended |  |  |  |  |  |  |  |  |  |  | 3 Months Ended | 6 Months Ended | 0 Months Ended | 6 Months Ended |  | 6 Months Ended
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Jun. 30, 2012 | Jun. 30, 2011 | Jun. 30, 2012 | Jun. 30, 2011 | Jan. 20, 2011 Platinum [Member] | Jun. 30, 2012 Interest Rate Contract [Member] | Dec. 31, 2011 Interest Rate Contract [Member] | Jun. 30, 2012 Foreign Currency Forward Contracts, Underwriting and Non-investment Operations [Member] | Dec. 31, 2011 Foreign Currency Forward Contracts, Underwriting and Non-investment Operations [Member] | Jun. 30, 2012 Foreign Currency Forward Contracts, Investment Operations [Member] | Dec. 31, 2011 Foreign Currency Forward Contracts, Investment Operations [Member] | Jun. 30, 2012 Foreign Currency Forward Contracts, Energy And Risk Operations [Member] | Dec. 31, 2011 Foreign Currency Forward Contracts, Energy And Risk Operations [Member] | Jun. 30, 2012 Credit Risk Contract [Member] | Dec. 31, 2011 Credit Risk Contract [Member] | Jun. 30, 2012 Energy And Weather Contracts [Member] Other (Loss) Income [Member] | Jun. 30, 2011 Energy And Weather Contracts [Member] Other (Loss) Income [Member] | Jun. 30, 2012 Energy And Weather Contracts [Member] Other (Loss) Income [Member] | Jun. 30, 2011 Energy And Weather Contracts [Member] Other (Loss) Income [Member] | Jan. 20, 2011 Platinum Warrant [Member] | Jan. 20, 2011 Platinum Warrant [Member] Other (Loss) Income [Member] | Jun. 30, 2012 Platinum Warrant [Member] Other (Loss) Income [Member] | Jun. 30, 2011 Platinum Warrant [Member] Other (Loss) Income [Member] | Jun. 30, 2012 Renaissance Trading [Member] Energy And Weather Contracts [Member] | Jun. 30, 2012 Value at Risk Valuation Technique [Member] Energy And Weather Contracts [Member]
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Notional amount of interest rate derivative purchase contracts |  |  |  |  |  | $ 360,200,000 | $ 3,200,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Notional amount of interest rate derivative sale contracts |  |  |  |  |  | 303,700,000 | 285,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Notional amount of foreign currency derivative purchase contracts |  |  |  |  |  |  |  | 179,700,000 | 160,500,000 | 198,300,000 | 48,100,000 | 0 | 7,800,000 |  |  |  |  |  |  |  |  |  |  |  |
Notional amount of foreign currency derivative sale contracts |  |  |  |  |  |  |  | 503,400,000 | 700,800,000 | 284,600,000 | 211,600,000 | 16,700,000 | 12,700,000 |  |  |  |  |  |  |  |  |  |  |  |
Notional amount of credit risk derivative purchase contracts |  |  |  |  |  |  |  |  |  |  |  |  |  | 15,000,000 | 15,000,000 |  |  |  |  |  |  |  |  |  |
Notional amount of credit risk derivative sale contracts |  |  |  |  |  |  |  |  |  |  |  |  |  | 24,400,000 | 38,100,000 |  |  |  |  |  |  |  |  |  |
Value at risk, likelihood of potential loss being within estimate |  |  | 99.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Value at risk, likelihood of potential loss exceeding estimate |  |  | 1.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Value at risk of portfolio at period end |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 42,000,000
Value at risk of portfolio during the period, average |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 26,400,000
Value at risk of portfolio during the period, minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 13,000,000
Value at risk of portfolio during the period, maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 49,300,000
Guarantees |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 354,300,000 |
Platinum Warrant, Shares |  |  |  |  | 2.5 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Platinum Warrant, in dollars per share |  |  |  |  | $ 27 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate proceeds from sale of Platinum Warrant |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 47,900,000 |  |  |  |  |
Derivative Instruments, Gain (Loss) Recognized in Income, Net | $ 9,208,000 | $ (4,600,000) | $ (18,476,000) | $ 906,000 |  |  |  |  |  |  |  |  |  |  |  | $ 11,987,000 | $ 1,429,000 | $ (16,726,000) | $ 9,929,000 |  | $ 3,000,000 | $ 0 | $ 2,975,000 |  |

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- Definition Exercise price of the warrants. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 + Details
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- Definition Aggregate notional amount of credit derivatives purchased to manage exposure to credit risk. Notional amount refers to the number of contracts multiplied by the contract size as specified in the credit derivative contract. + References No definition available. + Details
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- Definition Aggregate notional amount of credit derivatives sold to manage exposure to credit risk. Notional amount refers to the number of contracts multiplied by the contract size as specified in the credit derivative contract. + References No definition available. + Details
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- Definition Aggregate notional amount of interest rate futures contracts purchased to manage exposure to interest rate risk. Notional amount refers to the number of contracts multiplied by the contract size as specified in the interest rate futures contract. + References No definition available. + Details
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- Definition Value-at-risk (“VaR”) is a tool that measures the potential loss that could occur if trading positions were maintained over a defined period of time, calculated at a given statistical confidence level. + References No definition available. + Details
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- Definition VaR is a tool that measures the potential loss that could occur if the Company's trading positions were maintained over a defined period of time, calculated at a given statistical confidence level. + References No definition available. + Details
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- Definition VaR is a tool that measures the potential loss that could occur if the Company's trading positions were maintained over a defined period of time, calculated at a given statistical confidence level. + References No definition available. + Details
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- Definition VaR is a tool that measures the potential loss that could occur if the Company's trading positions were maintained over a defined period of time, calculated at a given statistical confidence level. + References No definition available. + Details
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- Definition The specified number of securities that each class of warrants or rights outstanding give the holder the right but not the obligation to purchase from the issuer at a specific price, on or before a certain date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 4 -Section 08 -Paragraph i -Subparagraph 2 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(i)(2)) -URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690 + Details
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- Definition The amount of net gains and losses recognized in income during the period on derivative instruments designated and qualifying as hedging instruments in fair value hedges and related hedged items designated and qualifying in fair value hedges, on derivative instruments designated and qualifying as hedging instruments in cash flow hedges, and on derivative instruments not designated as hedging instruments. + References Reference 1: 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. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5618551-113959 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (a),(c),(d),(e) -URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624171-113959 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 44C -Subparagraph b -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
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- Definition The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 5 -Paragraph 9 -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 FASB Interpretation (FIN) -Number 45 -Paragraph 13 -Subparagraph c -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 460 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248 + Details
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- Definition Aggregate notional amount of foreign currency derivatives to purchase a foreign currency. Notional amount refers to the number of currency units specified in the foreign currency derivative contract. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Notional Amount -URI http://asc.fasb.org/extlink&oid=6519104 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5579245-113959 + Details
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