Fair Value Measurements - Estimated Fair Values of Convertible Notes (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 29, 2012	Sep. 29, 2012
Estimated Fair Value Of Financial Instruments [Line Items]
Estimated fair values of debt instruments	$ 1,772,100	$ 1,767,900
2007 Notes [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Estimated fair values of debt instruments	771,100	771,600
2010 Notes [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Estimated fair values of debt instruments	504,700	505,600
2012 Notes [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Estimated fair values of debt instruments	$ 496,300	$ 490,700