Business Restructuring Charges - Changes in Restructuring Balance (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
CR Bard Inc
Restructuring Reserve [Roll Forward]
Beginning balance	$ 33	$ 0	$ 0
Charged to expense	118	292	0
Cash payments	(39)	(106)	0
Non-cash settlements	(89)	(153)	0
Other adjustments			0
Ending balance	23	33	0
CR Bard Inc | Employee Termination
Restructuring Reserve [Roll Forward]
Beginning balance	33	0	0
Charged to expense	23	136	0
Cash payments	(34)	(103)	0
Non-cash settlements	0	0	0
Other adjustments			0
Ending balance	22	33	0
CR Bard Inc | Other
Restructuring Reserve [Roll Forward]
Beginning balance	0	0	0
Charged to expense	95	156	0
Cash payments	(5)	(3)	0
Non-cash settlements	(89)	(153)	0
Other adjustments			0
Ending balance	1	0	0
CareFusion and Other Initiatives
Restructuring Reserve [Roll Forward]
Beginning balance		55	69
Charged to expense		52	85
Cash payments		(79)	(57)
Non-cash settlements		(1)	(9)
Other adjustments			(33)
Ending balance			55
CareFusion and Other Initiatives | Employee Termination
Restructuring Reserve [Roll Forward]
Beginning balance		49	67
Charged to expense		30	27
Cash payments		(56)	(45)
Non-cash settlements		0	0
Other adjustments			0
Ending balance			49
CareFusion and Other Initiatives | Other
Restructuring Reserve [Roll Forward]
Beginning balance		6	2
Charged to expense		22	58
Cash payments		(23)	(12)
Non-cash settlements		(1)	(9)
Other adjustments			(33)
Ending balance			$ 6
Other Initiatives
Restructuring Reserve [Roll Forward]
Beginning balance	27
Charged to expense	62
Cash payments	(52)
Non-cash settlements	(3)
Ending balance	34	27
Other Initiatives | Employee Termination
Restructuring Reserve [Roll Forward]
Beginning balance	23
Charged to expense	29
Cash payments	(21)
Non-cash settlements	0
Ending balance	31	23
Other Initiatives | Other
Restructuring Reserve [Roll Forward]
Beginning balance	4
Charged to expense	33
Cash payments	(31)
Non-cash settlements	(3)
Ending balance	$ 3	$ 4