Fair Value Measurements and Fair Value of Financial Instruments (Details 2) (USD $)	12 Months Ended
	Dec. 29, 2012	Dec. 31, 2011	Jan. 01, 2011
Available-for-sale investments, Other Disclosures
Cumulative unrealized loss related to the temporary impairment, net of tax	$ (1,141,000)	$ (1,664,000)
Other long-term assets - investments - deferred compensation plan
Deferred compensation plan	4,225,000	3,763,000
Unrealized gain before tax from the change in the value of the deferred compensation plan	400,000	200,000	400,000
Contractual maturities of available-for-sale investments, Amortized Cost
Total Amortized Cost	160,188,000	169,504,000
Contractual maturities of available-for-sale investments, Fair Value
Total Fair Value	159,033,000	166,843,000
Auction Rate Securities Sold | Minimum
Available-for-sale investments, Other Disclosures
Auction rate securities, rate setting interval	7 days
Short-term investments
Available-for-sale investments by major security type:
Amortized Cost	148,288,000	150,604,000
Gross Unrealized Gains	160,000	161,000
Gross Unrealized Losses	(22,000)	(13,000)
Fair Value	148,426,000	150,753,000
Contractual maturities of available-for-sale investments, Amortized Cost
Maturing within 1 year	107,621,000	128,602,000
Maturing after 1 year through 5 years	40,667,000	22,002,000
Total Amortized Cost	148,288,000	150,604,000
Maturing after 5 years	11,900,000	18,900,000
Contractual maturities of available-for-sale investments, Fair Value
Maturing within 1 year	107,665,000	128,744,000
Maturing after 1 year through 5 years	40,761,000	22,009,000
Total Fair Value	148,426,000	150,753,000
Maturing after 5 years	10,607,000	16,090,000
Municipal bonds
Available-for-sale investments by major security type:
Amortized Cost	107,416,000	97,406,000
Gross Unrealized Gains	136,000	160,000
Gross Unrealized Losses	(19,000)	(6,000)
Fair Value	107,533,000	97,560,000
Variable demand notes
Available-for-sale investments by major security type:
Amortized Cost	21,330,000	48,800,000
Fair Value	21,330,000	48,800,000
Corporate bonds
Available-for-sale investments by major security type:
Amortized Cost	12,244,000	4,398,000
Gross Unrealized Gains	17,000	1,000
Gross Unrealized Losses	(3,000)	(7,000)
Fair Value	12,258,000	4,393,000
Certificate of deposit
Available-for-sale investments by major security type:
Amortized Cost	2,000,000
Gross Unrealized Gains	6,000
Fair Value	2,006,000
Commercial Paper
Available-for-sale investments by major security type:
Amortized Cost	5,298,000
Gross Unrealized Gains	1,000
Fair Value	5,299,000
Long-term investments
Available-for-sale investments by major security type:
Amortized Cost	14,896,000
Gross Unrealized Losses	(1,687,000)
Fair Value	13,209,000
Long-term investments - auction rate securities
Available-for-sale investments by major security type:
Amortized Cost	11,900,000	18,900,000
Gross Unrealized Losses	(1,293,000)	(2,810,000)
Fair Value	10,607,000	16,090,000
Available-for-sale investments, Other Disclosures
Cumulative unrealized loss related to the auction rate securities, before tax	1,300,000
Cumulative unrealized loss related to the temporary impairment, net of tax	800,000
Percentage of the principal and accrued interest to be received from the issuer, not probable to be less than	100.00%
Percent of impairment charged to other comprehensive income (loss)	100.00%
Settlements of investments, at par	7,000,000
Maximum final maturity of the underlying notes to auction rate securities	35 years
Long-term investments - auction rate securities | Maximum
Available-for-sale investments, Other Disclosures
Auction rate securities, rate setting interval	35 days
Marketable equity securities
Available-for-sale investments by major security type:
Amortized Cost	2,996,000
Gross Unrealized Losses	(394,000)
Fair Value	$ 2,602,000