Note 6 - Investments Investments Trading Securities (Details) (USD $)	6 Months Ended		12 Months Ended
	Jun. 30, 2013		Dec. 31, 2012
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 3,722,975,000		$ 4,094,622,000
Securities (Assets)
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities, Change in Unrealized Holding (Loss) Gain	(142,800,000)		29,800,000
US government and agency securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	417,067,000		428,519,000
State and municipal obligations
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	641,210,000		669,975,000
Corporate bonds and notes
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	1,308,570,000		1,357,175,000
RMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	533,289,000		663,307,000
CMBS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	300,010,000		237,294,000
Other ABS
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	205,590,000		254,102,000
Foreign government securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	0	[1]	117,686,000	[1]
Hybrid Instrument [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	152,885,000		211,944,000
Equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	163,466,000		153,722,000
Other investments
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 888,000		$ 898,000

[1] As of June 30, 2013, there were no foreign government securities in our investment portfolio. We sold our investment in foreign government securities during the first quarter of 2013, as our market view of these investments changed, and their performance did not meet our expectations.