Net Sales to External Customers Based upon Geographic Location (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 31, 2012	Sep. 29, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Geographic Reporting Disclosure [Line Items]
Net sales to external customers	$ 89,895	$ 68,190	$ 68,329	$ 65,370	$ 80,670	$ 60,734	$ 66,762	$ 65,229	$ 291,784	$ 273,395	$ 254,164
UNITED STATES
Geographic Reporting Disclosure [Line Items]
Net sales to external customers									109,757	97,912	91,452
Germany
Geographic Reporting Disclosure [Line Items]
Net sales to external customers									42,471	42,413	45,658
Europe-Other
Geographic Reporting Disclosure [Line Items]
Net sales to external customers									60,944	57,698	53,910
Asia
Geographic Reporting Disclosure [Line Items]
Net sales to external customers									67,934	64,668	57,112
Americas-Other
Geographic Reporting Disclosure [Line Items]
Net sales to external customers									$ 10,678	$ 10,704	$ 6,032