Business Restructuring Charges - Summary of Restructuring Accrual Activity (Detail) $ in Millions	9 Months Ended
	Jun. 30, 2020 USD ($)
CR Bard Inc
Restructuring Reserve [Roll Forward]
Balance at September 30, 2019	$ 23
Charged to expense	40
Cash payments	(27)
Non-cash settlements	(21)
Balance at June 30, 2020	15
CR Bard Inc | Employee Termination
Restructuring Reserve [Roll Forward]
Balance at September 30, 2019	22
Charged to expense	7
Cash payments	(15)
Non-cash settlements	0
Balance at June 30, 2020	14
CR Bard Inc | Other Restructuring
Restructuring Reserve [Roll Forward]
Balance at September 30, 2019	1
Charged to expense	33
Cash payments	(12)
Non-cash settlements	(21)
Balance at June 30, 2020	1
Other Initiatives
Restructuring Reserve [Roll Forward]
Balance at September 30, 2019	34
Charged to expense	29
Cash payments	(46)
Non-cash settlements	(2)
Balance at June 30, 2020	15
Other Initiatives | Employee Termination
Restructuring Reserve [Roll Forward]
Balance at September 30, 2019	31
Charged to expense	(1)
Cash payments	(18)
Non-cash settlements	0
Balance at June 30, 2020	12
Other Initiatives | Other Restructuring
Restructuring Reserve [Roll Forward]
Balance at September 30, 2019	3
Charged to expense	30
Cash payments	(28)
Non-cash settlements	(2)
Balance at June 30, 2020	$ 3