Business Restructuring Charges - Changes in Restructuring Balance (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
CR Bard Inc
Restructuring Reserve [Roll Forward]
Beginning balance	$ 16	$ 23	$ 33
Charged to expense	3	49	118
Cash payments	(7)	(32)	(39)
Non-cash settlements	0	(24)	(89)
Other adjustments	1
Ending balance	11	16	23
CR Bard Inc | Employee Termination
Restructuring Reserve [Roll Forward]
Beginning balance	15	22	33
Charged to expense	1	7	23
Cash payments	(5)	(14)	(34)
Non-cash settlements	0	0	0
Other adjustments	1
Ending balance	10	15	22
CR Bard Inc | Other
Restructuring Reserve [Roll Forward]
Beginning balance	1	1	0
Charged to expense	2	42	95
Cash payments	(2)	(18)	(5)
Non-cash settlements	0	(24)	(89)
Other adjustments	0
Ending balance	1	1	1
Other Initiatives
Restructuring Reserve [Roll Forward]
Beginning balance	20	34	27
Charged to expense	47	46	62
Cash payments	(55)	(58)	(52)
Non-cash settlements	(4)	(2)	(3)
Other adjustments	0
Ending balance	8	20	34
Other Initiatives | Employee Termination
Restructuring Reserve [Roll Forward]
Beginning balance	17	31	23
Charged to expense	13	13	29
Cash payments	(26)	(27)	(21)
Non-cash settlements	0	0	0
Other adjustments	0
Ending balance	4	17	31
Other Initiatives | Other
Restructuring Reserve [Roll Forward]
Beginning balance	3	3	4
Charged to expense	34	33	33
Cash payments	(29)	(31)	(31)
Non-cash settlements	(4)	(2)	(3)
Other adjustments	0
Ending balance	$ 4	$ 3	$ 3