SUPPLEMENTAL CASH FLOW & OTHER DATA (Details) - USD ($) $ in Millions	1 Months Ended			3 Months Ended			9 Months Ended
	Oct. 23, 2020	Aug. 31, 2020	Apr. 30, 2020	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Supplemental Cash Flow Elements [Abstract]
Depreciation expense				$ 62		$ 59	$ 186	$ 175
Amortization expense				27		23	77	72
Depreciation and amortization expense				89		82	263	247
Interest expense				(42)		(45)	(126)	(136)
Interest income				0		1	2	3
Interest expense, net				(42)		(44)	(124)	(133)
Interest paid				33		58	136	149
Income taxes paid				148		65	168	148
Accounts payable associated with capital expenditures				55		24	55	24
Dividends payable				76		72	76	72
Fair value of assets acquired				126			377	61
Fair value of liabilities assumed				(9)		0	(29)	0
Fair value of net assets acquired				117			348	61
Merger consideration receivable/payable				2		0	2	(5)
Cash paid for business acquisitions				119		0	350	56
Less: Cash acquired				18		0	21	0
Business acquisitions, net of cash acquired				101			329	56
Leases:
Leased assets obtained in exchange for new operating lease liabilities				40		38	119	116
Leased assets obtained in exchange for new finance lease liabilities				0		$ 1	0	$ 1
CARES Act, amount received from initial tranche			$ 65
CARES Act, amount received from secondary tranche		$ 73
Accounts payable and accrued liabilities, CARES Act proceeds				138			138
CARES Act funds distributed to healthcare providers included in net cash provided by operating activities							$ 138
Other expense (income), net
Subsequent Event [Line Items]
CARES Act proceeds recognized in the statement of operations					$ 65
Reversal of recognition of CARES Act proceeds”				$ 65
Subsequent Event
Subsequent Event [Line Items]
CARES Act, funds decided to be returned	$ 138