Operating Segments and Geographic Data (Schedule Of Concentration Of Revenue From Individual Geographic Regions) (Details)	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017	Sep. 30, 2016
Revenue From External Customer [Line Items]
Document Period End Date	Sep. 28, 2018
Concentration of revenue from individual geographic regions	100.00%	100.00%	100.00%
U.S. [Member]
Revenue From External Customer [Line Items]
Concentration of revenue from individual geographic regions	33.00%	35.00%	31.00%
South Korea [Member]
Revenue From External Customer [Line Items]
Concentration of revenue from individual geographic regions	19.00%	16.00%	17.00%
China [Member]
Revenue From External Customer [Line Items]
Concentration of revenue from individual geographic regions	17.00%	16.00%	14.00%
Japan [Member]
Revenue From External Customer [Line Items]
Concentration of revenue from individual geographic regions	12.00%	12.00%	12.00%
Europe [Member]
Revenue From External Customer [Line Items]
Concentration of revenue from individual geographic regions	11.00%	11.00%	14.00%
Taiwan [Member]
Revenue From External Customer [Line Items]
Concentration of revenue from individual geographic regions	3.00%	4.00%	4.00%
Other [Member]
Revenue From External Customer [Line Items]
Concentration of revenue from individual geographic regions	5.00%	6.00%	8.00%