Segment Information - Operating results (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenues
Revenues	$ 33,480	$ 58,583	$ 107,975	$ 155,666
Operating income (loss) before goodwill and other asset impairments
Operating income (loss) before goodwill and other asset impairments	(3,109)	6,180	(8,456)	10,149
Corporate and other business activities	(10,100)	(11,003)	(30,379)	(32,095)
Interest expense	(627)	(778)	(1,883)	(2,468)
Impairment of marketable securities	(7,886)	0	(30,626)	0
Other income (expense), net	7,905	33	9,177	6,514
Income (loss) before income taxes and equity method income	(3,717)	5,435	(31,788)	14,195
Depreciation and amortization	5,864	5,950	17,768	18,127
Energy segment:
Revenues
Revenues	23,798	49,701	90,397	140,767
Operating income (loss) before goodwill and other asset impairments
Operating income (loss) before goodwill and other asset impairments	(498)	8,551	3,692	21,923
Depreciation and amortization	5,440	5,519	16,485	16,924
Sports segment:
Revenues
Revenues	9,682	8,882	17,578	14,899
Operating income (loss) before goodwill and other asset impairments
Operating income (loss) before goodwill and other asset impairments	789	1,146	(1,570)	(896)
Depreciation and amortization	424	431	1,283	1,203
Total segment operating income
Operating income (loss) before goodwill and other asset impairments
Operating income (loss) before goodwill and other asset impairments	291	9,697	2,122	21,027
Corporate and other business activities
Operating income (loss) before goodwill and other asset impairments
Corporate and other business activities	$ (3,400)	$ (3,517)	$ (10,578)	$ (10,878)