Goodwill and Other Intangible Assets - Additional Information (Details)	3 Months Ended
	Mar. 31, 2024 USD ($) reporting_unit	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Goodwill [Line Items]
Goodwill		$ 2,752,000,000	$ 2,752,000,000	$ 2,752,000,000
Number of reporting units | reporting_unit	3
Goodwill impairment charges	$ 0
Expected deductible goodwill for tax purpose		293,000,000
Accumulated impairment loss		0	0	$ 0
Commercial Bank
Goodwill [Line Items]
Goodwill		218,000,000	800,000,000
Percentage of estimated fair value in excess of carrying amount	25.00%
Institutional Bank
Goodwill [Line Items]
Goodwill		$ 715,000,000	$ 133,000,000
Percentage of estimated fair value in excess of carrying amount	34.00%
Consumer Bank
Goodwill [Line Items]
Percentage of estimated fair value in excess of carrying amount	18.00%