Note 6 - Investments Investments Trading Securities (Details) (USD $)	Mar. 31, 2012		Dec. 31, 2011
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 4,168,846,000		$ 4,211,059,000
US government and agency securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	712,402,000		710,006,000
State and municipal obligations
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	894,319,000		964,748,000
Corporate bonds and notes
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	703,196,000		683,864,000
RMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	886,477,000		928,887,000
CMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	215,267,000		224,180,000
CDO
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	6,403,000		5,467,000
Other ABS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	119,683,000		98,729,000
Foreign government securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	109,760,000	[1]	102,851,000	[1]
Portugal, Ireland, Italy, Greece and Spain Government Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	0		0
Number Of Stressed Eurozone Countries	5
German Foreign Government Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	27,500,000		42,600,000
Japanese Foreign Government Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	58,200,000		28,000,000
Convertible Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	367,265,000		346,338,000
Equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	148,089,000		140,764,000
Other investments
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 5,985,000		$ 5,225,000

[1] Our largest concentrations of foreign government securities as of March 31, 2012 and December 31, 2011, were Germany ($27.5 million and $42.6 million fair value, respectively) and Japan ($58.2 million and $28.0 million fair value, respectively). As of March 31, 2012 and December 31, 2011, nearly all of our foreign government securities were rated A or higher by a Nationally Recognized Statistical Rating Organization ("NRSRO"). As of March 31, 2012 and December 31, 2011, our trading portfolio included no securities of five Eurozone countries (Portugal, Ireland, Italy, Greece and Spain, collectively, the "Stressed Eurozone Countries") whose sovereign obligations have been under stress due to economic uncertainty, potential restructuring and ratings downgrades, or securities of any other countries under similar stress.