Segment Information - Summary of Segment Information Reconciled to Consolidated Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue:
Net premiums earned	$ 73,449	$ 51,998	$ 135,095	$ 103,182
Net investment income (loss)	1,604	4,226	1,412	7,504
Net realized investment gains (losses)	1,435	(133)	(809)	(505)
Net unrealized investment gains (losses)	2,884	1,326	(1,921)	6,619
Credit losses on investments	(87)	0	(526)	0
Policy fee income	847	800	1,676	1,595
Other	585	413	1,170	869
Total revenue	80,717	58,630	136,097	119,264
Expenses:
Losses and loss adjustment expenses	39,843	24,293	67,921	51,289
Amortization of deferred policy acquisition costs	12,511	8,770	23,368	17,426
Interest expense	3,020	2,884	5,990	7,221
Depreciation and amortization	480	384	957	778
Other	13,040	11,984	25,381	22,952
Total expenses	68,894	48,315	123,617	99,666
Income before income taxes	11,823	10,315	12,480	19,598
Operating Segments [Member] | Insurance Operations [Member]
Revenue:
Net premiums earned	73,449	51,998	135,095	103,182
Net investment income (loss)	2,076	3,388	4,409	6,016
Net realized investment gains (losses)	1,483	(132)	(339)	66
Net unrealized investment gains (losses)	2,473	1,108	(1,624)	5,418
Credit losses on investments	(87)		(526)
Policy fee income	847	800	1,676	1,595
Other	320	162	595	338
Total revenue	80,561	57,324	139,286	116,615
Expenses:
Losses and loss adjustment expenses	39,843	24,293	67,921	51,289
Amortization of deferred policy acquisition costs	12,511	8,770	23,368	17,426
Interest expense	1		1	1
Depreciation and amortization	27	26	58	53
Other	7,607	7,774	15,682	14,864
Total expenses	59,989	40,863	107,030	83,633
Income before income taxes	20,572	16,461	32,256	32,982
Total revenue from non-affiliates	80,561	57,324	139,286	116,615
Operating Segments [Member] | Real Estate Operations [Member]
Revenue:
Net investment income (loss)	2		3
Other	2,419	2,380	4,978	4,692
Total revenue	2,421	2,380	4,981	4,692
Expenses:
Interest expense	498	382	971	765
Depreciation and amortization	640	668	1,296	1,251
Other	1,406	1,466	2,657	2,574
Total expenses	2,544	2,516	4,924	4,590
Income before income taxes	(123)	(136)	57	102
Total revenue from non-affiliates	1,954	1,974	4,048	3,877
Operating Segments [Member] | Corporate and Other [Member]
Revenue:
Net investment income (loss)	104	1,096	(2,266)	1,603
Net realized investment gains (losses)	(48)	(1)	(470)	(571)
Net unrealized investment gains (losses)	411	218	(297)	1,201
Other	518	1,698	1,890	3,249
Total revenue	985	3,011	(1,143)	5,482
Expenses:
Interest expense	2,742	2,632	5,459	6,715
Depreciation and amortization	409	262	811	530
Other	6,460	6,127	12,420	11,723
Total expenses	9,611	9,021	18,690	18,968
Income before income taxes	(8,626)	(6,010)	(19,833)	(13,486)
Total revenue from non-affiliates	444	2,562	(2,182)	4,622
Intersegment Eliminations [Member]
Revenue:
Net investment income (loss)	(578)	(258)	(734)	(115)
Other	(2,672)	(3,827)	(6,293)	(7,410)
Total revenue	(3,250)	(4,085)	(7,027)	(7,525)
Expenses:
Interest expense	(221)	(130)	(441)	(260)
Depreciation and amortization	(596)	(572)	(1,208)	(1,056)
Other	(2,433)	(3,383)	(5,378)	(6,209)
Total expenses	$ (3,250)	$ (4,085)	$ (7,027)	$ (7,525)