Contractual Maturities of Investments Held (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 28, 2014
Schedule of Available-for-sale Securities
Due within one year, cost	$ 594,500
Due after 1 year through 5 years, cost	330,340
Due after 5 years through 10 years, cost	5,772
Due after 10 years, cost	25,032
Total, cost	955,644
Due within one year, fair value	594,801
Due after 1 year through 5 years, fair value	330,412
Due after 5 years through 10 years, fair value	5,859
Due after 10 years, fair value	26,438
Total, fair value	$ 957,510