Cash And Cash Equivalents And Investments (Schedule Of Investments By Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 29, 2012	Mar. 31, 2012
Available-for-sale securities:
Total short-term investments	$ 120,034	$ 111,137
Total long-term investments	13,500	25,900
Short-term Investments [Member]
Trading securities:
Due in one year or less	9,078	8,650
Available-for-sale securities:
Due in 12 months or less	45,807	62,504
Due in 12 to 24 months	20,990	29,903
Due in 24 to 36 months	28,488	2,682
Due in 36 to 49 months	15,671	7,398
Total short-term investments	120,034	111,137
Long-term Investments [Member]
Available-for-sale securities:
Due after ten years	$ 13,500	$ 25,900