Marketable Securities - Schedule of Amortized Cost and Estimated Fair Value of Debt Securities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 29, 2013	Mar. 31, 2013
Available For Sale Securities Debt Maturities Fair Value [Abstract]
Due in one year or less, Amortized Cost	$ 90,782
Due after one year through three years, Amortized Cost	151,994
Due after three years through five years, Amortized Cost	62,462
Due after five years, Amortized Cost	40,734
Total amortized cost of debt securities	345,972	357,608
Due in one year or less, Estimated Fair Value	90,923
Due after one year through three years, Estimated Fair Value	152,292
Due after three years through five years, Estimated Fair Value	62,115
Due after five years, Estimated Fair Value	41,171
Available-for-sale securities, Estimated Fair Value	$ 346,501	$ 359,974