Segment Information and Operations By Geographic Area (Schedule Of Net Revenue By Geography Periods) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2015	Sep. 28, 2014	Sep. 27, 2015	Sep. 28, 2014
Segment Reporting Information [Line Items]
Total net revenues	$ 341,893	$ 353,338	$ 939,832	$ 1,040,333
United States [Member]
Segment Reporting Information [Line Items]
Total net revenues	213,913	188,569	552,787	561,067
Americas Excluding United States [Member]
Segment Reporting Information [Line Items]
Total net revenues	5,823	5,335	13,194	15,150
United Kingdom [Member]
Segment Reporting Information [Line Items]
Total net revenues	27,850	38,933	80,965	122,707
EMEA Excluding United Kingdom [Member]
Segment Reporting Information [Line Items]
Total net revenues	49,875	69,488	153,862	192,943
Asia Pacific [Member]
Segment Reporting Information [Line Items]
Total net revenues	$ 44,432	$ 51,013	$ 139,024	$ 148,466