Investments (Unrealized Loss) (Details) - USD ($) $ in Thousands	Jun. 28, 2015	Mar. 29, 2015
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Fair Value Less than 12 months	$ 226,684	$ 105,588
Unrealized Loss Less than 12 months	(504)	(159)
Fair Value 12 months or Greater	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Fair Value Total	226,684	105,588
Unrealized Loss Total	(504)	(159)
Corporate bonds
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Fair Value Less than 12 months	157,548	67,367
Unrealized Loss Less than 12 months	(392)	(121)
Fair Value 12 months or Greater	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Fair Value Total	157,548	67,367
Unrealized Loss Total	(392)	(121)
Asset-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Fair Value Less than 12 months	20,082	17,736
Unrealized Loss Less than 12 months	(17)	(9)
Fair Value 12 months or Greater	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Fair Value Total	20,082	17,736
Unrealized Loss Total	(17)	(9)
U.S. government treasuries and agencies securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Fair Value Less than 12 months	46,048	18,478
Unrealized Loss Less than 12 months	(86)	(23)
Fair Value 12 months or Greater	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Fair Value Total	46,048	18,478
Unrealized Loss Total	(86)	(23)
Municipal bonds
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Fair Value Less than 12 months	2,002	1,001
Unrealized Loss Less than 12 months	(5)	(2)
Fair Value 12 months or Greater	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Fair Value Total	2,002	1,001
Unrealized Loss Total	(5)	(2)
International government bonds
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Fair Value Less than 12 months	1,004	1,006
Unrealized Loss Less than 12 months	(4)	(4)
Fair Value 12 months or Greater	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Fair Value Total	1,004	1,006
Unrealized Loss Total	$ (4)	$ (4)