Segment Information - Operating results (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues
Revenues	$ 35,610	$ 51,924	$ 74,495	$ 97,083
Operating income (loss) before goodwill and other asset impairments
Operating income (loss) before goodwill and other asset impairments	(1,843)	4,023	(5,347)	3,969
Corporate and other business activities	(10,078)	(10,980)	(20,279)	(21,092)
Interest expense	(614)	(822)	(1,256)	(1,690)
Impairment of marketable securities	(22,740)	0	(22,740)	0
Other income (expense), net	3,001	1,964	1,272	6,481
Income (loss) before income taxes and equity method income	(22,196)	5,165	(28,071)	8,760
Depreciation and amortization	5,910	6,014	11,904	12,177
Energy segment:
Revenues
Revenues	29,467	47,153	66,599	91,066
Operating income (loss) before goodwill and other asset impairments
Operating income (loss) before goodwill and other asset impairments	1,831	7,905	4,190	13,372
Depreciation and amortization	5,480	5,612	11,045	11,405
Sports segment:
Revenues
Revenues	6,143	4,771	7,896	6,017
Operating income (loss) before goodwill and other asset impairments
Operating income (loss) before goodwill and other asset impairments	180	(10)	(2,359)	(2,042)
Depreciation and amortization	430	402	859	772
Total segment operating income
Operating income (loss) before goodwill and other asset impairments
Operating income (loss) before goodwill and other asset impairments	2,011	7,895	1,831	11,330
Corporate and other business activities
Operating income (loss) before goodwill and other asset impairments
Corporate and other business activities	$ (3,854)	$ (3,872)	$ (7,178)	$ (7,361)