Business Combinations - Additional Information (Detail) - USD ($) shares in Millions, $ in Millions		3 Months Ended
	Dec. 01, 2022	Mar. 31, 2023	Dec. 31, 2022
Business Acquisition [Line Items]
Business acquisition, transaction costs		$ 244
Goodwill		12,560	$ 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	22
Business combination, Recognized identifiable assets acquired and liabilities assumed, Deposits	86,110	400
Business combination tangible book value	3,500
Business combination, price of acquisition, expected	6,250
Business acquisition, transaction costs		244
Goodwill	$ 2,407	$ 2,400
MUFG Union Bank [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Business acquisition, Equity interest issued or issuable, Number of shares	44