Note 6 - Investments Investments Trading Securities (Details) (USD $)	Jun. 30, 2012		Dec. 31, 2011
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 4,228,522,000		$ 4,211,059,000
US government and agency securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	703,786,000		710,006,000
State and municipal obligations
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	811,041,000		964,748,000
Corporate bonds and notes
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	819,654,000		683,864,000
RMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	968,695,000		928,887,000
CMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	184,917,000		224,180,000
CDO
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	0		5,467,000
Other ABS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	132,563,000		98,729,000
Foreign government securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	109,128,000	[1]	102,851,000	[1]
Portugal, Ireland, Italy, Greece, Spain and Hungary Government Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	0		0
Number Of Stressed European Countries	6
German Foreign Government Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	27,000,000		42,600,000
Japanese Foreign Government Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	58,900,000		28,000,000
Convertible Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	353,863,000		346,338,000
Equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	144,112,000		140,764,000
Other investments
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 763,000		$ 5,225,000

[1] Our largest concentrations of foreign government securities as of June 30, 2012 and December 31, 2011, were Germany ($27.0 million and $42.6 million fair value, respectively) and Japan ($58.9 million and $28.0 million fair value, respectively). As of June 30, 2012 and December 31, 2011, nearly all of our foreign government securities were rated A or higher by a nationally recognized statistical rating organization. As of June 30, 2012 and December 31, 2011, our trading portfolio included no securities of the six European countries (Portugal, Ireland, Italy, Greece, Spain, and Hungary) whose sovereign and sub-sovereign obligations have been under particular stress due to economic uncertainty, potential restructuring and ratings downgrades, or securities of any other countries under similar stress.