Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) [Abstract]
General and administrative expenses	$ (2,063)	$ (1,517)
Operating income (loss)	(2,063)	(1,517)
Interest and investment income	399	48
Interest expense	(5)	(5)
Other income (expense)	(617)	(526)
Income (loss) from continuing operations before income taxes and equity in net income (loss) of affiliates	(2,286)	(2,000)
Income tax (provision) benefit	(66,064)	(13,675)
Income (loss) from continuing operations before equity in net income (loss) of affiliates	(68,350)	(15,675)
Equity in net income (loss) of affiliates	139,714	46,494
(Loss) income from continuing operations	71,364	30,819
Income (loss) from discontinued operations, net of tax provision	(5)	(133)
Net (loss) income	71,359	30,686
Other comprehensive income (loss), net of tax	(3,038)	9,159
Comprehensive income (loss)	$ 68,321	$ 39,845
Net income (loss) per share: Basic
(Loss) income from continuing operations	$ 2.31	$ 1.00
Income (loss) from discontinued operations, net of tax
Net (loss) income	2.31	1.00
Net income (loss) per share: Diluted
(Loss) income from continuing operations	2.30	0.94
Income (loss) from discontinued operations, net of tax
Net (loss) income	$ 2.30	$ 0.94
Weighted average common shares outstanding:
Basic	30,933	30,933
Diluted	31,008	31,008