Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) [Abstract]
General and administrative expenses	$ (1,758)	$ (1,680)	$ (3,394)	$ (3,545)
Operating income (loss)	(1,758)	(1,680)	(3,394)	(3,545)
Interest and investment income	1,189	627	2,077	1,026
Interest expense	(6)	(6)	(11)	(11)
Other expense	(554)	(1,498)	(1,188)	(2,313)
Income (loss) from continuing operations before income taxes and equity in net income (loss) of affiliates	(1,129)	(2,557)	(2,516)	(4,843)
Income tax (provision) benefit	5,068	380	5,655	(65,684)
Income (loss) from continuing operations before equity in net income (loss) of affiliates	3,939	(2,177)	3,139	(70,527)
Equity in net income (loss) of affiliates	(3,455)		1,639	139,714
(Loss) income from continuing operations	484	(2,177)	4,778	69,187
Income (loss) from discontinued operations, net of tax provision	(37)		(37)	(5)
Net (loss) income	447	(2,177)	4,741	69,182
Other comprehensive income (loss), net of tax	628	179	7,772	(2,859)
Comprehensive income (loss)	$ 1,075	$ (1,998)	$ 12,513	$ 66,323
Net income (loss) per share: Basic
(Loss) income from continuing operations	$ 0.02	$ (0.07)	$ 0.15	$ 2.24
Income (loss) from discontinued operations, net of tax
Net (loss) income	0.02	(0.07)	0.15	2.24
Net income (loss) per share: Diluted
(Loss) income from continuing operations	0.02	(0.07)	0.15	2.21
Income (loss) from discontinued operations, net of tax
Net (loss) income	$ 0.02	$ (0.07)	$ 0.15	$ 2.21
Weighted average common shares outstanding:
Basic	30,933	30,933	30,933	30,933
Diluted	31,008	30,933	31,008	31,008