Borrowings and Credit Arrangements - Company's Borrowings (Detail) - USD ($) $ in Millions	Jun. 25, 2016	Sep. 26, 2015
Debt Instrument [Line Items]
Current debt obligations, net of debt discount	$ 333.4	$ 391.8
Convertible Notes Payable, Current	58.7	142.2
Convertible Notes	755.9	861.5
Total long-term debt obligations	3,088.8	3,248.0
Total debt obligations	3,422.2	3,639.8
Term Loan [Member]
Debt Instrument [Line Items]
Current debt obligations, net of debt discount	74.7	74.6
Long-term debt obligations, net of debt discount	1,344.7	1,399.8
Revolver [Member]
Debt Instrument [Line Items]
Current debt obligations, net of debt discount	0.0	175.0
Accounts Receivable Securitization [Member]
Debt Instrument [Line Items]
Current debt obligations, net of debt discount	200.0	0.0
2022 Notes [Member]
Debt Instrument [Line Items]
Long-term debt obligations, net of debt discount	$ 988.2	$ 986.7

Long term debt obligations without convertible notes.

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