Segment Information (Schedule Of Segment Revenue From Product Lines) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Jun. 30, 2012	Jun. 25, 2011
Segment Reporting Information [Line Items]
Product revenue, net	$ 99,006	$ 92,242
Audio Products [Member]
Segment Reporting Information [Line Items]
Product revenue, net	80,747	71,119
Energy Products [Member]
Segment Reporting Information [Line Items]
Product revenue, net	$ 18,259	$ 21,123

Aggregate revenue during the period from the sale of goods in the normal course of business, after deducting returns, allowances and discounts.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(a))

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

Name:	us-gaap_SalesRevenueGoodsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration