Share-Based Arrangements Compensation Arrangements by Share-based Payment Award (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012
Share-based Compensation Arrangement by Share-based Payment Award
Share-based compensation expense	$ 991	$ 1,229	$ 4,056	$ 4,809
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based compensation expense	377	403	1,227	1,474
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based compensation expense	496	711	2,480	3,007
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Share-based compensation expense	$ 118	$ 115	$ 349	$ 328