Note 6 - Investments - Net Gains (Losses) on Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Gain (Loss) on Securities [Line Items]
Fixed-maturities available for sale, net realized gain (loss)	$ 34,869	$ 11,262	$ (11,256)
Trading securities, net realized gain (loss)	4	(303)	(1,840)
Equity securities, net realized gain (loss)	353	(719)	532
Realized Gains (Losses) on Investments, Net	35,826	10,843	(12,094)
Impairment losses due to intent to sell	(1,401)	0	(1,744)
Net decrease (increase) in expected credit losses	(1,254)	0	0
Net unrealized gains (losses) on investments	10,960	33,220	(27,287)
Total net gains (losses) on investments	44,131	44,063	(41,125)
Net unrealized gains (losses) on investments still held	12,590	28,078	(24,720)
Other investments
Gain (Loss) on Securities [Line Items]
Other investments, net realized gain (loss)	600	603	470
Other Investments, net unrealized gains (losses) on investments still held	248	(174)	447
Fixed-maturities available for sale
Gain (Loss) on Securities [Line Items]
Gross investment gains from sales and redemptions	37,431	17,663	1,986
Gross investment losses from sales and redemptions	(2,562)	(6,401)	(13,242)
Trading securities
Gain (Loss) on Securities [Line Items]
Trading Securities, net unrealized gains (losses) on investments still held	10,583	16,346	(16,281)
Equity securities
Gain (Loss) on Securities [Line Items]
Equity Securities, net unrealized gains (losses) on investments still held	$ 1,759	$ 11,906	$ (8,886)