Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Consolidated Statements of Operations [Abstract]
General and administrative expenses	$ (1,803)	$ (1,636)
Operating income (loss)	(1,803)	(1,636)
Interest and investment income	1,602	888
Interest expense	(5)	(5)
Other expense	1,216	634
Income (loss) before income taxes and equity in net income (loss) of affiliates	(1,422)	(1,387)
Income tax (provision) benefit	(2,066)	587
Income (loss) before equity in net income (loss) of affiliates	(3,488)	(800)
Equity in net income (loss) of affiliates	42,004	5,094
Net income (loss)	38,516	4,294
Other comprehensive (loss) income, net of tax	(6,406)	7,144
Comprehensive income (loss)	$ 32,110	$ 11,438
Basic
Net income (loss) per share	$ 1.25	$ 0.14
Diluted
Net income (loss) per share	$ 1.23	$ 0.14
Weighted average common shares outstanding:
Basic	30,933	30,933
Diluted	31,008	31,008