Cash, Cash Equivalents and Short-Term Investments (Short-Term Investments by Security Type) (Detail) (USD $)	Sep. 29, 2012		Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 34,439,000		$ 51,710,000
Gross Unrealized Gains	42,000		47,000
Gross Unrealized Losses			17,000	[1]
Estimated Fair Value	34,481,000		51,740,000	[2]
Amortized Cost of investment with loss positions	0		12,800,000
Fair value of investments with loss positions	0		12,800,000
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12,021,000	[3]	22,454,000	[3]
Gross Unrealized Gains	3,000	[3]	6,000	[3]
Gross Unrealized Losses			2,000	[1],[3]
Estimated Fair Value	12,024,000	[3]	22,458,000	[3]
Municipal securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,470,000		4,315,000
Estimated Fair Value	1,470,000		4,315,000
Government-sponsored enterprise securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	20,948,000		19,033,000
Gross Unrealized Gains	39,000		32,000
Gross Unrealized Losses			15,000	[1]
Estimated Fair Value	20,987,000		19,050,000
US Treasury securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost			3,258,000
Gross Unrealized Gains			9,000
Estimated Fair Value			3,267,000
Bank certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost			2,650,000
Estimated Fair Value			$ 2,650,000

[1] As of September 29, 2012 there were no investments with loss positions. As of December 31, 2011, the cost and fair value of investments with loss positions was $12.8 million. We evaluated the nature of these investments, credit worthiness of the issuer and the duration of these impairments to determine if an other-than-temporary decline in fair value had occurred and concluded that these losses were temporary.

[2] Derived from December 31, 2011 audited financial statements.

[3] Corporate debt securities include investments in financial and corporate institutions. No single issuer represents a significant portion of the total corporate debt securities portfolio.