Cash, Cash Equivalents, and Investments - Components of Cash, Cash Equivalents, and Investments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jul. 01, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Cash	$ 34,467	$ 34,986
Cash equivalents	12,947	5,098
Money market instruments	460	5,076
Cash and cash equivalents	47,874	45,160	205,992	38,103
Short-term investments	135,289	105,105
Limited partnership interest (accounted for using cost method)	2,455	3,740
Long-term investments	243,108	238,255
Total	426,271	388,520
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	80,386	46,001
Long-term investments	109,780	100,072
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	26,910	17,666
Long-term investments	41,266	34,710
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	14,443	16,224
Long-term investments	14,140	17,846
Sovereign Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	7,383	3,986
Long-term investments	23,052	10,606
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	3,000
Corporate Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	1,669	2,131
Agency Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments	1,498	7,482
Long-term investments		29,441
Covered Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments		5,618
Long-term investments		5,564
Treasury Bills [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments		5,997
Long-term investments	$ 52,415	$ 36,276