Note 6 - Segment Information (Detail) - Revenue By Product Family (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011		Sep. 30, 2012	Sep. 30, 2011
Revenue By Product Family	$ 56,508	$ 52,962	[1]	$ 165,599	$ 149,058	[1]
DC To DC Converters [Member]
Revenue By Product Family	49,710	44,936	[1]	145,217	128,287	[1]
Lighting Control Products [Member]
Revenue By Product Family	$ 6,798	$ 8,026	[1]	$ 20,382	$ 20,771	[1]

[1] * 2011 Revenue associated with Audio Amplifiers has been included with DC to DC Converters to conform with current year presentation.