Business Combinations - Narrative (Details) - USD ($) $ in Millions		3 Months Ended		11 Months Ended
	May 01, 2023	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024
Business Acquisition [Line Items]
Decrease to estimated bargain purchase gain		$ 16
Provision for credit losses		1,884	$ 2,275
First Republic
Business Acquisition [Line Items]
Estimated bargain purchase gain	$ 2,700			$ 2,759
Decrease to estimated bargain purchase gain		16
Net income attributable to the acquisition since the acquisition date		668
Provision for credit losses	$ 1,200
First Republic | Noninterest revenue
Business Acquisition [Line Items]
Revenue attributable to the acquisition since the acquisition date		315
First Republic | Net interest income
Business Acquisition [Line Items]
Revenue attributable to the acquisition since the acquisition date		$ 1,300