Business Restructuring Charges - Summary of Restructuring Accrual Activity (Detail) $ in Millions	6 Months Ended
	Mar. 31, 2018 USD ($)
CR Bard Inc [Member]
Restructuring Reserve [Roll Forward]
Balance at September 30, 2017	$ 0
Charged to expense	216
Cash payments	(41)
Non-cash settlements	(55)
Other adjustments	0
Balance at March 31, 2018	120
CR Bard Inc [Member] | Employee Termination
Restructuring Reserve [Roll Forward]
Balance at September 30, 2017	0
Charged to expense	161
Cash payments	(41)
Non-cash settlements	0
Other adjustments	0
Balance at March 31, 2018	120
CR Bard Inc [Member] | Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Balance at September 30, 2017	0
Charged to expense	55
Cash payments	0
Non-cash settlements	(55)
Other adjustments	0
Balance at March 31, 2018	0
CareFusion and Other Initiatives [Member]
Restructuring Reserve [Roll Forward]
Balance at September 30, 2017	55
Charged to expense	39
Cash payments	(61)
Non-cash settlements	0
Other adjustments	1
Balance at March 31, 2018	34
CareFusion and Other Initiatives [Member] | Employee Termination
Restructuring Reserve [Roll Forward]
Balance at September 30, 2017	49
Charged to expense	24
Cash payments	(45)
Non-cash settlements	0
Other adjustments	0
Balance at March 31, 2018	28
CareFusion and Other Initiatives [Member] | Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Balance at September 30, 2017	6
Charged to expense	15
Cash payments	(16)
Non-cash settlements	0
Other adjustments	1
Balance at March 31, 2018	$ 6