SEGMENTS - Reconciliation of consolidated pretax income (loss) to segment adjusted EBITDA (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2023	Dec. 31, 2021	Dec. 31, 2020
SEGMENTS
Income (loss) before income taxes	$ (189)	$ (403)	$ (851)	$ (1,903)	$ (1,760)
Workforce rebalancing charges		52	71	39	918
Charges related to ceasing to use leased / fixed assets and lease terminations			80
Transaction-related costs	58	55	264	627	21
Stock-based compensation expense	31	16	113	71	64
Impairment expense			0	469
Interest expense	21	14	94	64	63
Depreciation of property, equipment and capitalized software	246	$ 339	900	1,300	1,445
Amortization expense	326		1,245	1,314	1,408
Corporate expense not allocated to the segments	56		77	154	153
Other adjustments	43		59	88	27
Segment adjusted EBITDA	$ 592		$ 2,052	$ 2,223	$ 2,337