ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Summary of Amounts Reclassification from AOCI to Net Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) from discontinued operations, net of tax	$ 2	$ 62
Income tax expense (benefit)	(11)	67
Net income (loss) attributable to Baxter stockholders	(15)	126
Other (income) expense, net	(6)	3
Costs of sales	(1,810)	(1,764)
Amounts reclassified from AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss) attributable to Baxter stockholders	(3)	(111)
Amounts reclassified from AOCI | CTA
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) from discontinued operations, net of tax	0	(126)
Income tax expense (benefit)	0	0
Net income (loss) attributable to Baxter stockholders	0	(126)
Amounts reclassified from AOCI | Pension and OPEB items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) from discontinued operations, net of tax	0	14
Income tax expense (benefit)	1	(1)
Net income (loss) attributable to Baxter stockholders	(2)	13
Other (income) expense, net	(3)	3
Income (loss), before tax	(3)	17
Less: Tax effect on pension settlement from Kidney Care separation	0	(3)
Amounts reclassified from AOCI | Gains (losses) on hedging activities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense (benefit)	0	(1)
Net income (loss) attributable to Baxter stockholders	(1)	2
Income (loss), before tax	(1)	3
Amounts reclassified from AOCI | Gains (losses) on hedging activities | Foreign exchange contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net	0	(1)
Amounts reclassified from AOCI | Gains (losses) on hedging activities | Interest rate contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Costs of sales	$ (1)	$ 4