Note 6 - Investments Investments Trading Securities (Details) (USD $)	9 Months Ended		12 Months Ended
	Sep. 30, 2012		Dec. 31, 2011
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 4,145,380,000		$ 4,211,059,000
Securities (Assets)
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities, Change in Unrealized Holding Gain (Loss)	41,900,000		112,100,000
US government and agency securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	775,329,000		710,006,000
State and municipal obligations
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	597,449,000		964,748,000
Corporate bonds and notes
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	804,592,000		683,864,000
RMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	931,817,000		928,887,000
CMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	190,280,000		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	220,074,000		98,729,000
Foreign government securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	115,652,000	[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		6
German Foreign Government Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	21,500,000		42,600,000
Japanese Foreign Government Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	62,800,000		28,000,000
Convertible Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	359,762,000		346,338,000
Equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	149,647,000		140,764,000
Other investments
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 778,000		$ 5,225,000

[1] Our largest concentrations of foreign government securities as of September 30, 2012 and December 31, 2011, were Germany ($21.5 million and $42.6 million fair value, respectively) and Japan ($62.8 million and $28.0 million fair value, respectively). As of September 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 September 30, 2012 and December 31, 2011, our trading portfolio included no foreign sovereign or sub-sovereign 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.