Investments (Available-for-Sale) (Details) - USD ($) $ in Thousands	Jun. 28, 2015	Mar. 29, 2015
U.S. government treasuries and agencies securities
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 144,133	$ 135,570
Gross Unrealized Gains	260	398
Gross Unrealized Losses	(86)	(23)
Estimated Fair Value	144,307	135,945
Money market funds
Schedule of Available-for-sale Securities [Line Items]
Cost	48,839	55,578
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	48,839	55,578
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Cost	36,752	31,830
Gross Unrealized Gains	13	9
Gross Unrealized Losses	(17)	(9)
Estimated Fair Value	36,748	31,830
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Cost	237,774	245,229
Gross Unrealized Gains	143	567
Gross Unrealized Losses	(392)	(121)
Estimated Fair Value	237,525	245,675
International government bonds
Schedule of Available-for-sale Securities [Line Items]
Cost	1,009	1,010
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(4)	(4)
Estimated Fair Value	1,005	1,006
Corporate commercial paper
Schedule of Available-for-sale Securities [Line Items]
Cost	1,200	4,999
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	1,200	4,999
Bank deposits
Schedule of Available-for-sale Securities [Line Items]
Cost	14,250	16,915
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	14,250	16,915
Repurchase agreements
Schedule of Available-for-sale Securities [Line Items]
Cost	434	191
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	434	191
Municipal bonds
Schedule of Available-for-sale Securities [Line Items]
Cost	5,991	6,001
Gross Unrealized Gains	38	45
Gross Unrealized Losses	(5)	(2)
Estimated Fair Value	6,024	6,044
Total available-for-sale investments
Schedule of Available-for-sale Securities [Line Items]
Cost	490,382	497,323
Gross Unrealized Gains	454	1,019
Gross Unrealized Losses	(504)	(159)
Estimated Fair Value	490,332	498,183
Less amounts classified as cash equivalents
Schedule of Available-for-sale Securities [Line Items]
Cost	50,473	60,068
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	50,473	60,068
Short-term investments
Schedule of Available-for-sale Securities [Line Items]
Cost	439,909	437,255
Gross Unrealized Gains	454	1,019
Gross Unrealized Losses	(504)	(159)
Estimated Fair Value	$ 439,859	$ 438,115