Segment Information (Schedule Of Segment Revenue From Product Lines) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Sep. 28, 2013	Sep. 29, 2012	Sep. 28, 2013	Sep. 29, 2012
Segment Reporting Information [Line Items]
Product revenue, net	$ 190,671	$ 193,774	$ 345,796	$ 292,780
Audio Products [Member]
Segment Reporting Information [Line Items]
Product revenue, net	179,912	177,915	323,578	258,662
Energy Products [Member]
Segment Reporting Information [Line Items]
Product revenue, net	$ 10,759	$ 15,859	$ 22,218	$ 34,118

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=26872669&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

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