Business Combinations - Additional Information (Detail) - USD ($) shares in Millions, $ in Millions			3 Months Ended		6 Months Ended
	Aug. 03, 2023	Dec. 01, 2022	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Mar. 31, 2023	Dec. 31, 2022
Business Acquisition [Line Items]
Repayment of debt					$ 1,644	$ 5,154
Business acquisition, transaction costs			$ 310	$ 197	554	197
Goodwill			12,486		12,486			$ 12,373
MUFG Union Bank [Member]
Business Acquisition [Line Items]
Payments to acquire businesses, gross		$ 5,500
Business combination, Recognized identifiable assets acquired and liabilities assumed, Financial liabilities		53,395
Business combination, Recognized identifiable assets acquired and liabilities assumed, Deposits		86,110
Repayment of debt	$ 936
Business combination tangible book value		3,500
Business combination, price of acquisition, expected		6,250
Business acquisition, transaction costs			310	$ 197	554	$ 197
Goodwill		$ 2,324	$ 2,300		$ 2,300
MUFG Union Bank [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Proceeds from issuance of common stock during acquisition	$ 24
MUFG Union Bank [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Business acquisition, Equity interest issued or issuable, Number of shares		44
Home Street Bank [Member]
Business Acquisition [Line Items]
Business combination, Recognized identifiable assets acquired and liabilities assumed, Financial liabilities							$ 22
Business combination, Recognized identifiable assets acquired and liabilities assumed, Deposits							$ 400