Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements of Operations [Abstract]
General and administrative expenses	$ (6,612)	$ (6,534)
Operating income (loss)	(6,612)	(6,534)
Interest and investment income	5,727	4,746
Interest expense	(24)	(26)
Other expense	(4,586)	(3,445)
Income (loss) from continuing operations before income taxes and equity in net income (loss) of affiliates	(5,495)	(5,259)
Income tax (provision) benefit	(6,153)	39,348
Income (loss) from continuing operations before equity in net income (loss) of affiliates	(11,648)	34,089
Equity in net income (loss) of affiliates	101,403	(24,412)
Income (loss) from continuing operations	89,755	9,677
Income (loss) from discontinued operations, net of tax		(63)
Net income (loss)	$ 89,755	$ 9,614
Basic
Income (loss) from continuing operations	$ 2.90	$ 0.31
Income (loss) from discontinued operations, net of tax
Net income (loss) per share	2.90	0.31
Diluted
Income (loss) from continuing operations	2.88	0.31
Income (loss) from discontinued operations, net of tax
Net income (loss) per share	$ 2.88	$ 0.31
Weighted average common shares outstanding:
Basic	30,933	30,933
Diluted	31,008	31,008