Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 29, 2012	Dec. 31, 2011
Assets:
Cash	$ 57,730	$ 47,502
Cash equivalents	56,668	68,803
Short-term—marketable securities	30,191	46,006
Non-qualified deferred compensation plan	4,528	3,635
Total	149,117	165,946
Liabilities:
Earnout payment liability	1,870	890
Non-qualified deferred compensation plan	4,528	3,635
Total	6,398	4,525
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash	0	0
Cash equivalents	39,071	40,793
Short-term—marketable securities	10,258	7,501
Non-qualified deferred compensation plan	4,528	3,635
Total	53,857	51,929
Liabilities:
Earnout payment liability	0	0
Non-qualified deferred compensation plan	4,528	3,635
Total	4,528	3,635
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash	0	0
Cash equivalents	17,597	28,010
Short-term—marketable securities	19,933	38,505
Non-qualified deferred compensation plan	0	0
Total	37,530	66,515
Liabilities:
Earnout payment liability	0	0
Non-qualified deferred compensation plan	0	0
Total	0	0
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash		0
Cash equivalents	0	0
Short-term—marketable securities	0	0
Non-qualified deferred compensation plan	0	0
Total	0	0
Liabilities:
Earnout payment liability	1,870	890
Non-qualified deferred compensation plan	0	0
Total	1,870	890
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash	57,730	47,502
Cash equivalents	56,668	68,803
Short-term—marketable securities	30,191	46,006
Non-qualified deferred compensation plan	4,528	3,635
Total	149,117	165,946
Liabilities:
Earnout payment liability	1,870	890
Non-qualified deferred compensation plan	4,528	3,635
Total	$ 6,398	$ 4,525