Business Restructuring Charges - Summary of Restructuring Accrual Activity (Detail) $ in Millions	9 Months Ended
	Jun. 30, 2019 USD ($)
CR Bard Inc
Restructuring Reserve [Roll Forward]
Balance at September 30, 2018	$ 33
Charged to expense	69
Cash payments	(29)
Non-cash settlements	(52)
Balance at June 30, 2019	21
CR Bard Inc | Employee Termination
Restructuring Reserve [Roll Forward]
Balance at September 30, 2018	33
Charged to expense	12
Cash payments	(25)
Non-cash settlements	0
Balance at June 30, 2019	20
CR Bard Inc | Other Restructuring
Restructuring Reserve [Roll Forward]
Balance at September 30, 2018	0
Charged to expense	57
Cash payments	(4)
Non-cash settlements	(52)
Balance at June 30, 2019	1
Other Initiatives
Restructuring Reserve [Roll Forward]
Balance at September 30, 2018	27
Charged to expense	30
Cash payments	(41)
Non-cash settlements	(3)
Balance at June 30, 2019	13
Other Initiatives | Employee Termination
Restructuring Reserve [Roll Forward]
Balance at September 30, 2018	23
Charged to expense	8
Cash payments	(21)
Non-cash settlements	0
Balance at June 30, 2019	10
Other Initiatives | Other Restructuring
Restructuring Reserve [Roll Forward]
Balance at September 30, 2018	4
Charged to expense	22
Cash payments	(20)
Non-cash settlements	(3)
Balance at June 30, 2019	$ 3