Business Restructuring Charges Business Restructuring Charges - Changes in Restructuring Balance (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
CR Bard Inc [Member]
Restructuring Reserve [Roll Forward]
Beginning balance	$ 0	$ 0	$ 0
Charged to expense	292	0	0
Cash payments	(106)	0	0
Non-cash settlements	(153)	0	0
Other adjustments	0	0	0
Ending balance	33	0	0
CR Bard Inc [Member] | Employee Termination
Restructuring Reserve [Roll Forward]
Beginning balance	0	0	0
Charged to expense	136	0	0
Cash payments	(103)	0	0
Non-cash settlements	0	0	0
Other adjustments	0	0	0
Ending balance	33	0	0
CR Bard Inc [Member] | Other
Restructuring Reserve [Roll Forward]
Beginning balance	0	0	0
Charged to expense	156	0	0
Cash payments	(3)	0	0
Non-cash settlements	(153)	0	0
Other adjustments	0	0	0
Ending balance	0	0	0
CareFusion and Other Initiatives [Member]
Restructuring Reserve [Roll Forward]
Beginning balance	55	69	62
Charged to expense	52	85	526
Cash payments	(79)	(57)	(148)
Non-cash settlements	(1)	(9)	(39)
Other adjustments	0	(33)	(332)
Ending balance	27	55	69
CareFusion and Other Initiatives [Member] | Employee Termination
Restructuring Reserve [Roll Forward]
Beginning balance	49	67	62
Charged to expense	30	27	81
Cash payments	(56)	(45)	(76)
Non-cash settlements	0	0	0
Other adjustments	0	0	0
Ending balance	23	49	67
CareFusion and Other Initiatives [Member] | Other
Restructuring Reserve [Roll Forward]
Beginning balance	6	2	0
Charged to expense	22	58	445
Cash payments	(23)	(12)	(72)
Non-cash settlements	(1)	(9)	(39)
Other adjustments	0	(33)	(332)
Ending balance	$ 4	$ 6	$ 2