Borrowings and Credit Arrangements - Company's Borrowings (Detail) (USD $)
Mar. 28, 2015
Sep. 27, 2014
Debt Instrument [Line Items]    
Current debt obligations, net of debt discount $ 581,700,000 $ 114,500,000
Convertible Notes Payable, Current 417,300,000 0
Convertible Notes 844,000,000 1,235,600,000
Total long-term debt obligations 3,358,100,000 4,153,200,000
Total debt obligations 3,939,800,000 4,267,700,000
Term Loan A    
Debt Instrument [Line Items]    
Current debt obligations, net of debt discount 149,500,000 99,600,000
Long-term debt obligations, net of debt discount 697,600,000 796,700,000
Term Loan B    
Debt Instrument [Line Items]    
Current debt obligations, net of debt discount 14,900,000 14,900,000
Long-term debt obligations, net of debt discount 816,500,000 1,120,900,000
Senior Notes    
Debt Instrument [Line Items]    
Long-term debt obligations, net of debt discount $ 1,000,000,000 $ 1,000,000,000