Fair Value Measurements - Estimated Fair Values of Convertible Notes (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 30, 2013	Sep. 29, 2012
Estimated Fair Value Of Financial Instruments [Line Items]
Estimated fair values of debt instruments	$ 1,859,900	$ 1,767,900
2007 Notes [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Estimated fair values of debt instruments	407,100	771,600
2010 Notes [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Estimated fair values of debt instruments	541,100	505,600
2012 Notes [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Estimated fair values of debt instruments	524,100	490,700
2013 Notes [Member]
Estimated Fair Value Of Financial Instruments [Line Items]
Estimated fair values of debt instruments	$ 387,600