Note 18 - Quarterly Financial Data (Unaudited) - Level 4 - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Net premiums earned (Note 8)	$ 302,140	$ 286,471	$ 249,295	$ 277,415	$ 301,486	$ 281,185	$ 299,166	$ 263,512	$ 1,115,321	$ 1,145,349	$ 1,014,007
Services revenue (Note 4)	11,440	33,943	28,075	31,927	40,031	42,509	39,303	32,753	105,385	154,596	144,972
Net investment income (Note 6)	38,115	36,255	38,723	40,944	41,432	42,756	43,761	43,847	154,037	171,796	152,475
Net gains (losses) on investments and other financial instruments	17,376	17,652	47,276	(22,027)	4,257	13,009	12,540	21,913	60,277	51,719	(42,476)
Provision for losses	56,664	88,084	304,418	35,951	34,619	29,231	47,427	20,754	485,117	132,031	104,641
Policy acquisition costs	7,395	10,166	6,015	7,413	6,783	6,435	6,203	5,893	30,989	25,314	25,265
Cost of services	21,600	24,353	17,972	22,141	27,278	29,044	27,845	24,157	86,066	108,324	98,124
Other operating expenses	81,641	69,377	60,582	69,110	80,894	76,384	70,046	78,805	280,710	306,129	280,818
Loss on extinguishment of debt (Note 12)					0	5,940	16,798	0	0	22,738	0
Impairment of goodwill					4,828	0	0	0	0	4,828	0
Amortization and impairment of other acquired intangible assets	2,225	961	979	979	15,823	2,139	2,139	2,187	5,144	22,288	12,429
Net income	$ 148,013	$ 135,103	$ (29,951)	$ 140,461	$ 161,184	$ 173,438	$ 166,730	$ 170,957	$ 393,626	$ 672,309	$ 606,011
Diluted net income per share	$ 0.76	$ 0.70	$ (0.15)	$ 0.70	$ 0.79	$ 0.83	$ 0.78	$ 0.78	$ 2.00	$ 3.20	$ 2.77
Weighted-average number of common and common equivalent shares outstanding—diluted	194,663	194,156	193,299	201,819	205,165	208,691	213,603	218,343	196,642	210,340	218,553