Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidated Statements of Operations [Abstract]
General and administrative expenses	$ (6,726)	$ (6,530)	$ (5,330)
Operating income (loss)	(6,726)	(6,530)	(5,330)
Interest and investment income	194	138	581
Interest expense	(20)	(17)	(15)
Other income (expense)	(1,449)	(3,779)	(3,266)
Income (loss) from continuing operations before income taxes and equity in net income (loss) of affiliates	(8,001)	(10,188)	(8,030)
Income tax (provision) benefit	(28,507)	45,476	8,105
Income (loss) from continuing operations before equity in net income (loss) of affiliates	(36,508)	35,288	75
Equity in net income (loss) of affiliates	84,078	(104,792)	(1,502)
Income (loss) from continuing operations	47,570	(69,504)	(1,427)
Income (loss) from discontinued operations, net of tax provision	(370)	(778)	(24,402)
Net (loss) income	$ 47,200	$ (70,282)	$ (25,829)
Basic
Income (loss) from continuing operations	$ 1.54	$ (2.25)	$ (0.05)
Income (loss) from discontinued operations, net of tax	(0.01)	(0.03)	(0.79)
Net income (loss)	1.53	(2.28)	(0.84)
Diluted
Income (loss) from continuing operations	1.50	(2.25)	(0.05)
Income (loss) from discontinued operations, net of tax	(0.01)	(0.03)	(0.79)
Net income (loss)	$ 1.49	$ (2.28)	$ (0.84)
Weighted average common shares outstanding:
Basic	30,933	30,928	30,920
Diluted	31,008	30,928	30,920