Cash, Cash Equivalents and Investments - Components of Cash, Cash Equivalents and Investments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Oct. 02, 2011	Jan. 03, 2011
Schedule of Available-for-sale Securities [Line Items]
Cash	$ 43,260	$ 36,404
Cash equivalents	6,799
Money market instruments	4,099	1,699
Cash and cash equivalents	54,158	38,103	30,175	33,203
Short-term investments	101,870	144,431
Limited partnership interest (accounted for using cost method)	5,562	5,933
Long-term investments	259,910	174,906
Total	415,938	357,440
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	45,025	55,570
Long-term investments	91,839	59,902
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	25,257	54,036
Long-term investments	58,586	69,680
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	12,184
Long-term investments	35,018
Treasury Bills [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	10,043	1,945
Long-term investments	35,989
Covered Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	4,664	1,319
Long-term investments	2,757	4,701
Agency Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	2,998	27,545
Long-term investments	24,025	12,335
Sovereign Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	1,699	4,016
Long-term investments	$ 6,134	$ 22,355