Note 6 - Investments Net Gains (Losses) on Investments and Other Financial Instruments (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Gain (Loss) on Securities [Line Items]
Other gains (losses), net realized gain (loss)										$ 66	$ 32	$ 64
Realized Gains (Losses) on Investments, Net										(12,094)	(8,603)	4,313
Other than Temporary Impairment Losses, Investments										(1,744)	(1,420)	(526)
Net unrealized gains (losses) on trading securities	[1]									(27,287)	13,230	27,217
Total net gains (losses) on investments										(41,125)	3,207	31,004
Net gains (losses) on other financial instruments										(1,351)	414	(253)
Net Gains (Losses) on Investments and Other Financial Instruments		$ (11,705)	$ (4,480)	$ (7,404)	$ (18,887)	$ (1,339)	$ 2,480	$ 5,331	$ (2,851)	(42,476)	3,621	30,751
Fixed-maturities available for sale
Gain (Loss) on Securities [Line Items]
Fixed-maturities available for sale, net realized gain (loss)	[2]									(11,256)	(3,014)	4,160
Gross investment gains from sales and redemptions										1,986	6,052	10,326
Gross investment losses from sales and redemptions										(13,242)	(9,066)	(6,166)
Trading Securities
Gain (Loss) on Securities [Line Items]
Trading securities, net realized gain (loss)										(1,840)	(5,995)	(237)
Equity securities
Gain (Loss) on Securities [Line Items]
Equity securities, net realized gain (loss)										532	368	(170)
Short-term Investments
Gain (Loss) on Securities [Line Items]
Short-term investments, net realized gain (loss)										(10)	(16)	(135)
Other investments
Gain (Loss) on Securities [Line Items]
Other invested assets, net realized gain (loss)										$ 414	$ 22	$ 631

[1] These amounts include unrealized gains (losses) on investment securities other than securities available for sale. For 2017 and 2016, the unrealized gains (losses) on investments exclude the net change in unrealized gains and losses on equity securities. Prior to the implementation of the update to the standard for the accounting of financial instruments effective January 1, 2018, the unrealized gains (losses) associated with equity securities were classified in accumulated other comprehensive income.

[2] Components of net realized gains (losses) on fixed-maturities available for sale include:   Year Ended December 31, (In thousands) 2018   2017   2016 Gross investment gains from sales and redemptions $ 1,986
  $ 6,052
  $ 10,326
Gross investment losses from sales and redemptions (13,242 )   (9,066 )   (6,166 )