Segment Information - Operating results (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Revenues
Revenues	$ 45,159	$ 26,351
Operating income (loss)
Operating income (loss)	(54)	(26)
Corporate and other business activities	(10,903)	(7,712)
Interest income, net	721	623
Other income, net	2,928	1,139
Income from continuing operations before income taxes and equity method loss	3,595	1,736
Depreciation and amortization	6,163	4,994
Energy segment:
Revenues
Revenues	43,913	26,039
Operating income (loss)
Operating income (loss)	5,467	3,227
Depreciation and amortization	5,793	4,855
Sports segment:
Revenues
Revenues	1,246	312
Operating income (loss)
Operating income (loss)	(2,032)	(986)
Depreciation and amortization	370	139
Total segment operating income
Operating income (loss)
Operating income (loss)	3,435	2,241
Corporate and other business activities
Operating income (loss)
Corporate and other business activities	$ (3,489)	$ (2,267)