Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) [Abstract]
General and administrative expenses	$ (1,674)	$ (2,080)	$ (3,191)	$ (3,697)
Operating income (loss)	(1,674)	(2,080)	(3,191)	(3,697)
Interest and investment income	48	14	96	104
Interest expense	(4)	(5)	(9)	(8)
Other income (expense)	(593)	(2,710)	(1,119)	(3,084)
Income (loss) from continuing operations before income taxes and equity in net income (loss) of affiliates	(2,223)	(4,781)	(4,223)	(6,685)
Income tax (provision) benefit	(8,480)	(2,279)	(22,155)	(6,033)
Income (loss) from continuing operations before equity in net income (loss) of affiliates	(10,703)	(7,060)	(26,378)	(12,718)
Equity in net income (loss) of affiliates	43,357	25,087	89,851	(51,758)
Income (loss) from continuing operations	32,654	18,027	63,473	(64,476)
Income (loss) from discontinued operations, net of tax provision	(102)	(227)	(235)	(366)
Net income (loss)	32,552	17,800	63,238	(64,842)
Other comprehensive income (loss), net of tax	417	1,128	9,576	1,362
Comprehensive income (loss)	$ 32,969	$ 18,928	$ 72,814	$ (63,480)
Net income (loss) per share: Basic
Income (loss) from continuing operations	$ 1.06	$ 0.58	$ 2.05	$ (2.09)
Income (loss) from discontinued operations, net of tax		(0.01)	(0.01)	(0.01)
Net income (loss)	1.06	0.57	2.04	(2.10)
Net income (loss) per share: Diluted
Income (loss) from continuing operations	1.03	0.56	1.98	(2.09)
Income (loss) from discontinued operations, net of tax		(0.01)	(0.01)	(0.01)
Net income (loss)	$ 1.03	$ 0.55	$ 1.97	$ (2.10)
Weighted average common shares outstanding:
Basic	30,933	30,927	30,933	30,923
Diluted	31,008	31,006	31,008	30,923