Receivables (Detail) - USD ($) $ in Millions	Sep. 27, 2019	Sep. 28, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade and unbilled receivables, gross	$ 1,193.5	$ 1,093.0
Allowance for doubtful accounts	(46.5)	(41.1)
Trade and unbilled receivables, net	1,147.0	1,051.9
Short-term	1,106.3	1,009.9
Long-term (1)	40.7	42.0
Notes Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable	33.6	29.8
Short-term (2)	0.0	0.1
Long-term (1) (3)	$ 33.6	$ 29.7