v2.4.0.6

Derivative Instruments (Narrative) (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended		0 Months Ended											3 Months Ended		0 Months Ended		3 Months Ended			3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Jan. 20, 2011 Platinum [Member]	Mar. 31, 2012 Interest Rate Contract [Member]	Dec. 31, 2011 Interest Rate Contract [Member]	Mar. 31, 2012 Foreign Currency Forward Contracts, Underwriting and Non-investment Operations [Member]	Mar. 31, 2011 Foreign Currency Forward Contracts, Underwriting and Non-investment Operations [Member]	Mar. 31, 2012 Foreign Currency Forward Contracts, Investment Operations [Member]	Mar. 31, 2011 Foreign Currency Forward Contracts, Investment Operations [Member]	Mar. 31, 2012 Foreign Currency Forward Contracts, Energy And Risk Operations [Member]	Mar. 31, 2011 Foreign Currency Forward Contracts, Energy And Risk Operations [Member]	Mar. 31, 2012 Credit Risk Contract [Member]	Mar. 31, 2011 Credit Risk Contract [Member]	Mar. 31, 2012 Energy And Weather Contracts [Member] Other (Loss) Income [Member]	Mar. 31, 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]	Mar. 31, 2012 Platinum Warrant [Member] Other (Loss) Income [Member]	Mar. 31, 2011 Platinum Warrant [Member] Other (Loss) Income [Member]	Mar. 31, 2012 Renaissance Trading [Member] Energy And Weather Contracts [Member]	Mar. 31, 2012 Value at Risk Valuation Technique [Member] Energy And Weather Contracts [Member]
Derivative [Line Items]
Notional amount of interest rate derivative purchase contracts				$ 385,300,000	$ 3,200,000,000
Notional amount of interest rate derivative sale contracts				215,100,000	285,700,000
Notional amount of foreign currency derivative purchase contracts						236,600,000	160,500,000	126,300,000	48,100,000	21,200,000	7,800,000
Notional amount of foreign currency derivative sale contracts						575,500,000	700,800,000	217,600,000	211,600,000	13,300,000	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												23,800,000	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																					13,600,000
Value at risk of portfolio during the period, average																					28,600,000
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																				361,000,000
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	$ (27,684,000)	$ 5,506,000												$ (28,713,000)	$ 8,500,000		$ 3,000,000	$ 0	$ 2,975,000

X

- Definition

Exercise price of the warrants.

+ References

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

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- Definition

Derivative Asset, Proceeds from Sale

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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

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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.

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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.

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Aggregate notional amount of interest rate futures contracts sold 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.

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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.

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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.

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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

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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.

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The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

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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.

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Aggregate notional amount of foreign currency derivatives to sell a foreign currency. Notional amount refers to the number of currency units specified in the foreign currency derivative contract.

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