Loans and Leases - Loans and Leases Classified by Primary Purpose (Details) - USD ($) $ in Millions		Mar. 31, 2024	Dec. 31, 2023
Loans and leases held for sale:
Total loans and leases held for sale	[1]	$ 339	$ 378
Portfolio loans and leases:
Total portfolio loans and leases		116,485	117,234
Commercial
Portfolio loans and leases:
Total portfolio loans and leases		71,916	72,746
Commercial | Commercial and industrial loans
Loans and leases held for sale:
Total loans and leases held for sale		30	41
Portfolio loans and leases:
Total portfolio loans and leases		52,209	53,270
Commercial | Commercial leases
Loans and leases held for sale:
Total loans and leases held for sale		2	3
Portfolio loans and leases:
Total portfolio loans and leases		2,572	2,579
Commercial | Commercial mortgage loans
Portfolio loans and leases:
Total portfolio loans and leases		11,346	11,276
Commercial | Commercial construction loans
Portfolio loans and leases:
Total portfolio loans and leases		5,789	5,621
Consumer
Portfolio loans and leases:
Total portfolio loans and leases		44,569	44,488
Consumer | Residential mortgage loans
Loans and leases held for sale:
Total loans and leases held for sale		307	334
Portfolio loans and leases:
Total portfolio loans and leases		16,995	17,026
Consumer | Home equity
Portfolio loans and leases:
Total portfolio loans and leases		3,883	3,916
Consumer | Indirect secured consumer loans
Portfolio loans and leases:
Total portfolio loans and leases		15,306	14,965
Consumer | Credit card
Portfolio loans and leases:
Total portfolio loans and leases		1,737	1,865
Consumer | Solar energy installation loans
Portfolio loans and leases:
Total portfolio loans and leases		3,871	3,728
Consumer | Other consumer loans
Portfolio loans and leases:
Total portfolio loans and leases		$ 2,777	$ 2,988

[1] Includes $307 and $334 of residential mortgage loans held for sale measured at fair value at March 31, 2024 and December 31, 2023, respectively.