Business Combinations - Summary of Preliminary Fair Value of The Identifiable Tangible and Intangible Assets and Liabilities (Detail) - USD ($) $ in Millions		Dec. 01, 2022	Mar. 31, 2023	Dec. 31, 2022
Liabilities
Goodwill			$ 12,560	$ 12,373
MUFG Union Bank [Member]
Acquisition consideration
Cash		$ 5,500
Market value of shares of common stock		2,014
Total consideration transferred at acquisition close date		7,514
Discounted liability to MUFG (a)	[1]	2,944
Total		10,458
Assets
Cash and due from banks		17,754
Investment securities		22,725
Loans held for sale		2,220
Loans		53,395	22
Less allowance for loan losses		(463)
Net loans		52,932
Premises and Equipment		646
Other intangible assets (excluding goodwill)		2,808
Other assets		4,700
Total assets		103,785
Liabilities
Deposits		86,110	400
Short-term borrowings		4,773
Long-term debt		2,584
Other liabilities		2,267
Total liabilities		95,734
Less: Net assets		8,051
Goodwill		$ 2,407	$ 2,400

[1] Represents $3.5 billion of noninterest-bearing additional capital held by MUB upon close of the acquisition to be delivered to MUFG on or prior to December 1, 2027, discounted at the Company’s 5-year unsecured borrowing rate as of the acquisition date, per authoritative accounting guidance.