Investments (Details) (USD $)	3 Months Ended
	Apr. 01, 2012	Jan. 01, 2012
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Held to Maturity Securities, Debt Maturities, Term	5 years
Restricted long-term marketable securities	$ 9,087,000	$ 9,145,000	[1]
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Money market funds	$ 166,000,000	$ 187,500,000

[1] As adjusted to reflect the balances of Tenesol S.A. ("Tenesol") beginning October 10, 2011, as required under the accounting guidelines for a transfer of an entity under common control (see Note 3).