Goodwill and Other Intangible Assets - Gross Carrying Amount, Accumulated Amortization and Net Carrying Amount of Other Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 3,929	$ 3,879
Accumulated amortization	(2,883)	(2,790)
Net carrying amount	1,046	1,089	$ 1,320
Client relationships
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	2,743	2,706
Accumulated amortization	(1,982)	(1,919)
Net carrying amount	761	787
Technology
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	403	401
Accumulated amortization	(263)	(252)
Net carrying amount	140	149
Core deposits
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	685	677
Accumulated amortization	(555)	(540)
Net carrying amount	130	137
Other
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	98	95
Accumulated amortization	(83)	(79)
Net carrying amount	$ 15	$ 16