Investments and Fair Value Measurements (Details 5) (USD $) In Thousands, unless otherwise specified	Jan. 01, 2012
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	$ 884,480
Less than 12 months, Gross Unrealized Loss	(5,220)
Greater than 12 months, Fair Value	21,713
Greater than 12 months, Gross Unrealized Loss	(50)
U.S. Treasury and government agency securities [Member]
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	23,680
Less than 12 months, Gross Unrealized Loss	(4)
Greater than 12 months, Fair Value	0
Greater than 12 months, Gross Unrealized Loss	0
U.S. Government-sponsored agency securities [Member]
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	79,922
Less than 12 months, Gross Unrealized Loss	(26)
Greater than 12 months, Fair Value	0
Greater than 12 months, Gross Unrealized Loss	0
Corporate notes and bonds [Member]
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	311,254
Less than 12 months, Gross Unrealized Loss	(3,889)
Greater than 12 months, Fair Value	0
Greater than 12 months, Gross Unrealized Loss	0
Asset-backed securities [Member]
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	122,694
Less than 12 months, Gross Unrealized Loss	(149)
Greater than 12 months, Fair Value	0
Greater than 12 months, Gross Unrealized Loss	0
Municipal notes and bonds [Member]
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	346,930
Less than 12 months, Gross Unrealized Loss	(1,152)
Greater than 12 months, Fair Value	21,713
Greater than 12 months, Gross Unrealized Loss	$ (50)