Note 8 - Reinsurance - Effect of Reinsurance Programs (Details) - USD ($)	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
Premiums Written, Net [Abstract]
Direct Premiums Written									$ 1,108,513,000	$ 1,132,338,000	$ 1,089,720,000
Assumed Premiums Written									12,197,000	10,379,000	6,901,000
Ceded Premiums Written									(87,201,000)	(56,132,000)	(98,314,000)
Net premiums written—insurance									1,033,509,000	1,086,585,000	998,307,000
Premiums Earned, Net [Abstract]
Direct Premiums Earned									1,286,527,000	1,244,870,000	1,074,298,000
Assumed Premiums Earned									12,213,000	10,382,000	6,904,000
Ceded Premiums Earned									(183,419,000)	(109,903,000)	(67,195,000)
Net premiums earned—insurance	$ 302,140,000	$ 286,471,000	$ 249,295,000	$ 277,415,000	$ 301,486,000	$ 281,185,000	$ 299,166,000	$ 263,512,000	1,115,321,000	1,145,349,000	1,014,007,000
Ceded Credit Risk [Line Items]
Ceding commissions earned									53,654,000	48,659,000	33,446,000
Ceded losses									58,266,000	5,859,000	$ 5,086,000
Deferred ceding commissions	$ 52,500,000				$ 74,800,000				$ 52,500,000	$ 74,800,000