REVENUES - Additional Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue From Contract With Customer [Line Items]
Net trade accounts receivable	$ 1,800	$ 1,700
Sales-type lease, net of investment in lease	119
Sales-type leases, receivables	$ 15	$ 33	$ 26	$ 29	$ 16
Minimum
Revenue From Contract With Customer [Line Items]
Global payment terms	30 days
Minimum | Software sales
Revenue From Contract With Customer [Line Items]
Revenue recognized contract period	1 year
Minimum | Consumable Medical Products
Revenue From Contract With Customer [Line Items]
Revenue recognized contract period	1 year
Maximum
Revenue From Contract With Customer [Line Items]
Global payment terms	90 days
Maximum | Contract manufacturing services
Revenue From Contract With Customer [Line Items]
Revenue recognized contract period	90 days
Maximum | Software sales
Revenue From Contract With Customer [Line Items]
Revenue recognized contract period	5 years
Maximum | Consumable Medical Products
Revenue From Contract With Customer [Line Items]
Revenue recognized contract period	7 years