Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) [Abstract]
General and administrative expenses	$ (1,517)	$ (1,617)
Operating income (loss)	(1,517)	(1,617)
Interest and investment income	48	90
Interest expense	(5)	(3)
Other income (expense)	(526)	(374)
Income (loss) from continuing operations before income taxes and equity in net income (loss) of affiliates	(2,000)	(1,904)
Income tax (provision) benefit	(20,587)	(3,754)
Income (loss) from continuing operations before equity in net income (loss) of affiliates	(22,587)	(5,658)
Equity in net income (loss) of affiliates	46,494	(76,845)
Income (loss) from continuing operations	23,907	(82,503)
Income (loss) from discontinued operations, net of tax provision	(133)	(139)
Net income (loss)	23,774	(82,642)
Other comprehensive income (loss), net of tax	9,159	234
Comprehensive income (loss)	$ 32,933	$ (82,408)
Net income (loss) per share: [Abstract]
Income (loss) from continuing operations	$ 0.77	$ (2.67)
Income (loss) from discontinued operations, net of tax
Net income (loss)	$ 0.77	$ (2.67)
Net income (loss) per share:, Diluted [Abstract]
Income (loss) from continuing operations	$ 0.72	$ (2.67)
Income (loss) from discontinued operations, net of tax
Net income (loss)	$ 0.72	$ (2.67)
Weighted average common shares outstanding:
Basic	30,933	30,920
Diluted	31,008	30,920