Line Of Credit (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Jan. 01, 2011
Line of Credit Facility [Line Items]
Outstanding balance under credit facility	$ 21.2	$ 19.2
Interest rate of credit facility	2.00%	2.00%
Unused and available portion of credit facility	18.8	20.8
Line Of Credit Agreement [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under credit facility		35.0
Amended And Restated Line Of Credit Agreement [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under credit facility		40.0
Expiration date of credit facility	July 28, 2013
Eurocurrency Loans [Member]
Line of Credit Facility [Line Items]
Debt instrument rate, minimum	1.75%
Debt instrument rate, maximum	2.25%
Eurocurrency Loans [Member] | Amended And Restated Line Of Credit Agreement [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under credit facility	10.0
Committed Loans [Member] | Amended And Restated Line Of Credit Agreement [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under credit facility	30.0
Letters Of Credit [Member] | Amended And Restated Line Of Credit Agreement [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity under credit facility	$ 7.5
LIBOR [Member] | Amended And Restated Line Of Credit Agreement [Member]
Line of Credit Facility [Line Items]
Debt instrument rate, minimum	1.75%
Debt instrument rate, maximum	2.25%
Federal Fund Rate [Member] | Amended And Restated Line Of Credit Agreement [Member]
Line of Credit Facility [Line Items]
Debt instrument rate, minimum	0.25%
Debt instrument rate, maximum	0.75%
Federal Fund Rate [Member] | Committed Loans [Member] | Amended And Restated Line Of Credit Agreement [Member]
Line of Credit Facility [Line Items]
Basis spread on federal funds rate	50.00%