Derivative Instruments (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Fair Values of Derivative Instruments
Fair value of derivative liabilities	$ 211,617	$ 190,653
Consolidated Entity excluding Variable Interest Entities VIE [Member]
Fair Values of Derivative Instruments
Derivative Asset, Fair Value	393,348	448,566
Fair value of derivative liabilities	654,473	687,867
Credit Derivatives [Member]
Fair Values of Derivative Instruments
Fair value of derivative liabilities	(211,617)	(190,653)
Derivatives Assets [Member] | Consolidated Entity excluding Variable Interest Entities VIE [Member] | Derivatives held for trading [Member]
Fair Values of Derivative Instruments
Derivative Asset, Fair Value	393,348	442,511
Derivatives Assets [Member] | Interest Rate Swap [Member] | Consolidated Entity excluding Variable Interest Entities VIE [Member] | Derivatives held for trading [Member]
Fair Values of Derivative Instruments
Derivative Assets, Fair Value	392,766	411,652
Derivative Liabilities, Fair Value	259,852	242,500
Derivatives Assets [Member] | Call Option [Member] | Consolidated Entity excluding Variable Interest Entities VIE [Member]
Fair Values of Derivative Instruments
Derivative Assets, Fair Value		6,055
Derivatives Liability [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Values of Derivative Instruments
Derivative Asset, Fair Value		27,779
Fair value of derivative liabilities	2,063,809	2,114,831
Derivatives Liability [Member] | Consolidated Entity excluding Variable Interest Entities VIE [Member] | Derivatives held for trading [Member]
Fair Values of Derivative Instruments
Fair value of derivative liabilities	654,473	687,867
Derivatives Liability [Member] | Interest Rate Swap [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Values of Derivative Instruments
Fair value of derivative liabilities	1,978,737	2,023,974
Derivatives Liability [Member] | Interest Rate Swap [Member] | Consolidated Entity excluding Variable Interest Entities VIE [Member] | Derivatives held for trading [Member]
Fair Values of Derivative Instruments
Fair value of derivative liabilities	180,713	251,303
Derivative Asset, Fair Value	582	30,859
Derivatives Liability [Member] | Credit Derivatives [Member] | Consolidated Entity excluding Variable Interest Entities VIE [Member] | Derivatives held for trading [Member]
Fair Values of Derivative Instruments
Fair value of derivative liabilities	211,617	190,653
Derivatives Liability [Member] | Currency Swap [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Values of Derivative Instruments
Fair value of derivative liabilities	85,072	90,857
Derivative Asset, Fair Value		27,779
Derivatives Liability [Member] | Currency Swap [Member] | Consolidated Entity excluding Variable Interest Entities VIE [Member] | Derivatives held for trading [Member]
Fair Values of Derivative Instruments
Fair value of derivative liabilities	570	2,423
Derivatives Liability [Member] | Futures Contracts [Member] | Consolidated Entity excluding Variable Interest Entities VIE [Member] | Derivatives held for trading [Member]
Fair Values of Derivative Instruments
Fair value of derivative liabilities	1,541	627
Derivatives Liability [Member] | Other contracts [Member] | Consolidated Entity excluding Variable Interest Entities VIE [Member] | Derivatives held for trading [Member]
Fair Values of Derivative Instruments
Fair value of derivative liabilities	$ 180	$ 361