Changes in Carrying Amount of Goodwill (Detail) (USD $) In Thousands, unless otherwise specified			3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 LED Replacement lamps and fixtures	Mar. 31, 2014 LED Signage and Lighting Strips
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 21,523	$ 21,523	$ 21,523
Transfer of Relume's Media business			(1,453)	1,453
Goodwill	23,919		22,059	1,860
Accumulated impairment losses	(2,396)		(1,989)	(407)
Goodwill, Ending Balance	$ 21,523	$ 21,523	$ 20,070	$ 1,453