Geographic Data (Net Sales By Country) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Oct. 01, 2011	Jul. 02, 2011	Apr. 02, 2011	Dec. 31, 2010	Oct. 02, 2010	Jul. 03, 2010	Apr. 03, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Segment Reporting Information [Line Items]
Net sales	$ 247,308	$ 253,338	$ 245,541	$ 237,301	$ 234,019	$ 229,807	$ 218,558	$ 211,975	$ 983,488	$ 894,359	$ 738,482
United States [Member]
Segment Reporting Information [Line Items]
Net sales									504,283	482,891	438,946
United Kingdom [Member]
Segment Reporting Information [Line Items]
Net sales									339,027	303,604	253,548
Singapore [Member]
Segment Reporting Information [Line Items]
Net sales									136,757	105,286	42,144
Other [Member]
Segment Reporting Information [Line Items]
Net sales									$ 3,421	$ 2,578	$ 3,844