Note 8 - Reinsurance Effect of Reinsurance Programs (Details) - USD ($)		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Premiums Written, Net [Abstract]
Direct Premiums Written										$ 1,132,338,000		$ 1,089,720,000		$ 1,032,735,000
Assumed Premiums Written										10,379,000	[1]	6,901,000	[1]	25,000
Ceded Premiums Written	[2]									(56,132,000)		(98,314,000)		(214,343,000)
Net premiums written—insurance										1,086,585,000		998,307,000		818,417,000
Premiums Earned, Net [Abstract]
Direct Premiums Earned										1,244,870,000		1,074,298,000		990,016,000
Assumed Premiums Earned										10,382,000	[1]	6,904,000	[1]	28,000
Ceded Premiums Earned	[2]									(109,903,000)		(67,195,000)		(57,271,000)
Net premiums earned—insurance		$ 301,486,000	$ 281,185,000	$ 299,166,000	$ 263,512,000	$ 261,682,000	$ 258,431,000	$ 251,344,000	$ 242,550,000	1,145,349,000		1,014,007,000		932,773,000
Ceded Credit Risk [Line Items]
Ceding commissions earned	[3]									48,659,000		33,446,000		26,896,000
Ceded losses										5,859,000		5,086,000		$ 3,261,000
Deferred ceding commissions		$ 74,800,000				$ 91,400,000				$ 74,800,000		$ 91,400,000

[1] Includes premiums earned from our participation in certain credit risk transfer programs.

[2] Net of profit commission.

[3] Deferred ceding commissions of $74.8 million and $91.4 million are included in other liabilities on our consolidated balance sheets at December 31, 2019 and 2018, respectively.