Notes Payable (Details) (Line of Credit, Brokerage Firm, USD $) In Millions, unless otherwise specified	Jun. 29, 2013	Dec. 31, 2012
Line of Credit Facility [Line Items]
Maximum borrowing percent of cash, cash equivalents and investments balance	75.00%
Line of credit facility amount outstanding	$ 1.0	$ 1.0
Line of credit facility collateral requirement	$ 1.3	$ 1.3
Federal Funds Open Rate
Line of Credit Facility [Line Items]
Line of credit facility basis points	1.25%
Line of credit facility interest rate	1.30%