Investments and Fair Value Measurements (Details 5) (USD $) In Thousands, unless otherwise specified	Apr. 01, 2012
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	$ 670,263
Less than 12 months, Gross Unrealized Loss	(2,127)
Greater than 12 months, Fair Value	17,073
Greater than 12 months, Gross Unrealized Loss	(31)
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	42,145
Less than 12 months, Gross Unrealized Loss	(12)
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	61,020
Less than 12 months, Gross Unrealized Loss	(27)
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	170,152
Less than 12 months, Gross Unrealized Loss	(516)
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	43,643
Less than 12 months, Gross Unrealized Loss	(46)
Greater than 12 months, Fair Value	0
Greater than 12 months, Gross Unrealized Loss	0
Mortgage Backed Securities, Other [Member]
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	1,537
Less than 12 months, Gross Unrealized Loss	(2)
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	351,766
Less than 12 months, Gross Unrealized Loss	(1,524)
Greater than 12 months, Fair Value	17,073
Greater than 12 months, Gross Unrealized Loss	$ (31)