Fair Value Measurements - Carrying Amounts and Estimated Fair Value for Financial Instrument Assets (Liabilities) (Detail) - USD ($) $ in Millions		Mar. 31, 2025	Dec. 31, 2024
Cash and cash equivalents
Interest-bearing deposits at banks		$ 20,656	$ 18,873
Investment securities held to maturity		35,137	34,051
Net loans and leases		132,374	133,397
Financial liabilities:
Short-term borrowings		73	60
Loan facility carrying amount	[1]	10,496	12,605
Level 1
Cash and cash equivalents
Cash and cash equivalents		1,980	1,749
Interest-bearing deposits at banks		0	0
Investment securities held to maturity		0	0
Net loans and leases		0	0
Financial liabilities:
Time deposits		0	0
Short-term borrowings		0	0
Loan facility carrying amount		0	0
Level 2
Cash and cash equivalents
Cash and cash equivalents		129	160
Interest-bearing deposits at banks		20,656	18,873
Investment securities held to maturity		12,264	12,909
Net loans and leases		6,653	6,806
Financial liabilities:
Time deposits		13,948	14,463
Short-term borrowings		1,573	1,060
Loan facility carrying amount		10,605	12,754
Level 3
Cash and cash equivalents
Cash and cash equivalents		0	0
Interest-bearing deposits at banks		0	0
Investment securities held to maturity		44	46
Net loans and leases		125,342	124,528
Financial liabilities:
Time deposits		0	0
Short-term borrowings		0	0
Loan facility carrying amount		0	0
Carrying Amount
Cash and cash equivalents
Cash and cash equivalents		2,109	1,909
Interest-bearing deposits at banks		20,656	18,873
Investment securities held to maturity		13,352	14,195
Net loans and leases		132,374	133,397
Financial liabilities:
Time deposits		13,979	14,476
Short-term borrowings		1,573	1,060
Loan facility carrying amount		10,496	12,605
Estimated Fair Value
Cash and cash equivalents
Cash and cash equivalents		2,109	1,909
Interest-bearing deposits at banks		20,656	18,873
Investment securities held to maturity		12,308	12,955
Net loans and leases		131,995	131,334
Financial liabilities:
Time deposits		13,948	14,463
Short-term borrowings		1,573	1,060
Loan facility carrying amount		$ 10,605	$ 12,754

[1] Loans and leases of $2.1 billion and $1.5 billion at March 31, 2025 and December 31, 2024, respectively, were held in special purpose trusts to settle the respective obligations of asset-backed notes issued by those trusts. The outstanding balances of those asset-backed notes were included in Long-term borrowings and were $1.8 billion at March 31, 2025 and $1.2 billion at December 31, 2024.