Schedule II - Statement of Operations and Comprehensive Income (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Debt Securities, Available-for-sale	$ 1,489,383	$ 1,377,959
Other long-term investments	27,294	385
Short-term investments	0	1,301
Cash and cash equivalents	34,131	46,205
Accrued investment income	16,137	17,453
Property and equipment, net	16,312	5,904
Other assets	5,086	2,489
Total assets	1,843,420	1,744,936
Total liabilities	1,542,475	1,485,100
Accumulated deficit	(82,352)	(70,969)
Unrealized investment gains on securities held by parent and subsidaries, net of tax	128,255	77,117
Treasury stock	(11,011)	(11,011)
Total stockholders' equity	300,945	259,836	$ 187,733	$ 223,513
Total liabilities and stockholders' equity	1,843,420	1,744,936
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Investment in subsidiary	231,992	191,869
Debt Securities, Available-for-sale	42,202	50,491
Equity securities	1,347	1,167
Real estate and other long-term investments	2,571	2,571
Other long-term investments	8,790	0
Short-term investments	0	1,301
Cash and cash equivalents	3,102	10,829
Accrued investment income	471	535
Accounts receivable from subsidiaries	4,911	4,770
Property and equipment, net	12,666	817
Other assets	3,183	552
Total assets	311,235	264,902
Accrued expenses and other liabilities	10,290	5,066
Total liabilities	10,290	5,066
Accumulated deficit	(82,352)	(70,969)
Unrealized investment gains on securities held by parent and subsidaries, net of tax	128,255	77,117
Treasury stock	(11,011)	(11,011)
Total stockholders' equity	300,945	259,836
Total liabilities and stockholders' equity	311,235	264,902
Common Class A [Member]
Condensed Financial Statements, Captions [Line Items]
Common stock	262,869	261,515
Common Class A [Member] | Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Common stock	262,869	261,515
Common Class B [Member]
Condensed Financial Statements, Captions [Line Items]
Common stock	3,184	3,184
Common Class B [Member] | Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Common stock	$ 3,184	$ 3,184