Loans and Leases - Loans and Leases Classified by Primary Purpose (Details) - USD ($) $ in Millions		Sep. 30, 2021	Dec. 31, 2020
Loans and leases held for sale:
Loans and leases held for sale	[1]	$ 5,203	$ 4,741
Portfolio loans and leases:
Commercial and industrial loans		47,834	49,665
Commercial mortgage loans		10,300	10,602
Commercial construction loans		5,456	5,815
Commercial leases		3,130	2,915
Residential mortgage loans		16,158	15,928
Home equity		4,276	5,183
Indirect secured consumer loans		16,004	13,653
Credit card		1,744	2,007
Other consumer loans		3,009	3,014
Total portfolio loans and leases	[2],[3]	107,911	108,782
Residential mortgage loans
Loans and leases held for sale:
Loans and leases held for sale		5,201	4,465
Residential mortgage loans | GNMA loans
Portfolio loans and leases:
Total portfolio loans and leases			39
Commercial
Portfolio loans and leases:
Total portfolio loans and leases		66,720	68,997
Commercial | Commercial and industrial loans
Loans and leases held for sale:
Loans and leases held for sale		2	230
Portfolio loans and leases:
Total portfolio loans and leases		47,834	49,665
Loans and leases related to SBA Paycheck Protection Program of CARES Act		2,300	4,800
Commercial | Commercial mortgage loans
Loans and leases held for sale:
Loans and leases held for sale		0	7
Commercial | Commercial leases
Loans and leases held for sale:
Loans and leases held for sale		0	39
Portfolio loans and leases:
Total portfolio loans and leases		3,130	2,915
Consumer
Portfolio loans and leases:
Total portfolio loans and leases		$ 41,191	39,785
Consumer | Residential mortgage loans | GNMA loans
Portfolio loans and leases:
Total portfolio loans and leases			$ 39

[1] Includes $1,532 and $1,481 of residential mortgage loans held for sale measured at fair value at September 30, 2021 and December 31, 2020, respectively.

[2] Includes $156 and $161 of residential mortgage loans measured at fair value at September 30, 2021 and December 31, 2020, respectively.

[3] Includes $27 and $55 of other short-term investments, $383 and $756 of portfolio loans and leases, $(3) and $(7) of ALLL, $2 and $5 of other assets, $1 and $2 of other liabilities, and $325 and $656 of long-term debt from consolidated VIEs that are included in their respective captions above at September 30, 2021 and December 31, 2020, respectively. For further information, refer to Note 12.