Consolidated Statements of Stockholder's Equity Statement - USD ($) $ in Thousands	Total	Accumulated deficit [Member]	Accumulated other comprehensive income [Member]	Treasury stock [Member]	Common Stock Class A [Member] Common stock [Member]	Common Stock Class B [Member] Common stock [Member]
Balance at Dec. 31, 2018	$ 187,733	$ (69,599)	$ 5,366	$ (11,011)	$ 259,793	$ 3,184
Net income (loss)	(3,802)	(3,802)	0	0	0	0
Unrealized investment gains (losses), net	26,880	0	26,880	0	0	0
Comprehensive income (loss)	23,078	(3,802)	26,880	0	0	0
Stock-based compensation	1,083	0	0	0	1,083	0
Balance at Mar. 31, 2019	211,894	(73,401)	32,246	(11,011)	260,876	3,184
Balance at Dec. 31, 2019	259,836	(70,969)	77,117	(11,011)	261,515	3,184
Net income (loss)	(3,584)	(3,584)	0	0	0	0
Unrealized investment gains (losses), net	(40,070)	0	(40,070)	0	0	0
Comprehensive income (loss)	(43,654)	(3,584)	(40,070)	0	0	0
Stock-based compensation	(53)	0	0	0	(53)	0
Balance at Mar. 31, 2020	$ 215,734	$ (74,948)	$ 37,047	$ (11,011)	$ 261,462	$ 3,184