Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Consolidated Statements of Operations [Abstract]
General and administrative expense	$ (6,534)	$ (7,044)
Operating income (loss)	(6,534)	(7,044)
Interest and investment income	4,746	2,483
Interest expense	(26)	(27)
Other expense	(3,445)	(4,182)
Income (loss) from continuing operations before income taxes and equity in net income (loss) of affiliates	(5,259)	(8,770)
Income tax (provision) benefit	39,348	(73,108)
Income (loss) from continuing operations before equity in net income (loss) of affiliates	34,089	(81,878)
Equity in net income (loss) of affiliates	(24,412)	216,347
Income (loss) from continuing operations	9,677	134,469
Income (loss) from discontinued operations, net of tax	(63)	(5)
Net income (loss)	$ 9,614	$ 134,464
Basic
Income (loss) from continuing operations	$ 0.31	$ 4.35
Income (loss) from discontinued operations, net of tax
Net income (loss)	0.31	4.35
Diluted
Income (loss) from continuing operations	0.31	4.30
Income (loss) from discontinued operations, net of tax
Net income (loss)	$ 0.31	$ 4.30
Weighted average common shares outstanding:
Basic	30,933	30,933
Diluted	31,008	31,008