ACCUMULATED OTHER COMPREHENSIVE INCOME - Summary of Amounts Reclassification from AOCI to Net Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense, net	$ (12)	$ (16)	$ (15)	$ (32)
Income tax (benefit) expense	1	(56)	(141)	(143)
Cost of sales	(1,905)	(1,777)	(5,571)	(5,096)
Income before income taxes	451	415	1,194	1,082
Net income (loss) attributable to Baxter	450	356	1,046	934
Amounts reclassified from AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss) attributable to Baxter	(22)	(12)	(71)	(33)
Amortization of pension and OPEB items | Amounts reclassified from AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense, net	(21)	(14)	(62)	(44)
Income tax (benefit) expense	4	3	12	9
Net income (loss) attributable to Baxter	(17)	(11)	(50)	(35)
Gains (losses) on hedging activities | Amounts reclassified from AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax (benefit) expense	1	1	6	0
Income before income taxes	(6)		(27)
Net income (loss) attributable to Baxter	(5)	(1)	(21)	2
Gains (losses) on hedging activities | Foreign exchange contracts | Amounts reclassified from AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	(5)	$ (2)	(23)	$ 2
Gains (losses) on hedging activities | Interest rate contracts | Amounts reclassified from AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net	$ (1)		$ (4)