Fair Value Measurements - Carrying Amounts and Estimated Fair Values for Certain Financial Instruments (Details) - USD ($) $ in Millions		Mar. 31, 2023	Dec. 31, 2022
Financial assets:
Other short-term investments	[1]	$ 9,794	$ 8,351
Held-to-maturity securities	[2]	2	5
Loans and leases held for sale	[3]	749	1,007
Total portfolio loans and leases, net		120,642	119,286
Financial liabilities:
Deposits		162,975	163,690
Federal funds purchased		177	180
Other short-term borrowings		7,364	4,838
Long-term debt	[1]	12,893	13,714
Commercial
Financial assets:
Total portfolio loans and leases, net		77,239	76,389
Consumer
Financial assets:
Total portfolio loans and leases, net		45,618	45,091
Net Carrying Amount
Financial assets:
Cash and due from banks		2,780	3,466
Other short-term investments		9,794	8,351
Other securities		890	874
Held-to-maturity securities		2	5
Loans and leases held for sale		150	407
Total portfolio loans and leases, net		120,514	119,163
Financial liabilities:
Deposits		162,975	163,690
Federal funds purchased		177	180
Other short-term borrowings		7,364	4,838
Long-term debt		12,868	13,778
Net Carrying Amount | Commercial
Financial assets:
Total portfolio loans and leases, net		76,096	75,262
Net Carrying Amount | Consumer
Financial assets:
Total portfolio loans and leases, net		44,418	43,901
Total Fair Value
Financial assets:
Cash and due from banks		2,780	3,466
Other short-term investments		9,794	8,351
Other securities		890	874
Held-to-maturity securities		2	5
Loans and leases held for sale		154	414
Total portfolio loans and leases, net		119,441	117,297
Financial liabilities:
Deposits		162,924	163,634
Federal funds purchased		177	180
Other short-term borrowings		7,362	4,829
Long-term debt		12,294	13,629
Total Fair Value | Commercial
Financial assets:
Total portfolio loans and leases, net		76,271	75,104
Total Fair Value | Consumer
Financial assets:
Total portfolio loans and leases, net		43,170	42,193
Total Fair Value | Level 1
Financial assets:
Cash and due from banks		2,780	3,466
Other short-term investments		9,794	8,351
Other securities		0	0
Held-to-maturity securities		0	0
Loans and leases held for sale		0	0
Total portfolio loans and leases, net		0	0
Financial liabilities:
Deposits		0	0
Federal funds purchased		177	180
Other short-term borrowings		0	0
Long-term debt		11,900	13,218
Total Fair Value | Level 1 | Commercial
Financial assets:
Total portfolio loans and leases, net		0	0
Total Fair Value | Level 1 | Consumer
Financial assets:
Total portfolio loans and leases, net		0	0
Total Fair Value | Level 2
Financial assets:
Cash and due from banks		0	0
Other short-term investments		0	0
Other securities		890	874
Held-to-maturity securities		0	0
Loans and leases held for sale		0	0
Total portfolio loans and leases, net		0	0
Financial liabilities:
Deposits		162,924	163,634
Federal funds purchased		0	0
Other short-term borrowings		7,362	4,829
Long-term debt		394	411
Total Fair Value | Level 2 | Commercial
Financial assets:
Total portfolio loans and leases, net		0	0
Total Fair Value | Level 2 | Consumer
Financial assets:
Total portfolio loans and leases, net		0	0
Total Fair Value | Level 3
Financial assets:
Cash and due from banks		0	0
Other short-term investments		0	0
Other securities		0	0
Held-to-maturity securities		2	5
Loans and leases held for sale		154	414
Total portfolio loans and leases, net		119,441	117,297
Financial liabilities:
Deposits		0	0
Federal funds purchased		0	0
Other short-term borrowings		0	0
Long-term debt		0	0
Total Fair Value | Level 3 | Commercial
Financial assets:
Total portfolio loans and leases, net		76,271	75,104
Total Fair Value | Level 3 | Consumer
Financial assets:
Total portfolio loans and leases, net		$ 43,170	$ 42,193

[1] Includes $5 and $17 of other short-term investments, $44 and $185 of portfolio loans and leases, $(1) and $(2) of ALLL, $0 and $2 of other assets, $9 and $9 of other liabilities, and $38 and $118 of long-term debt from consolidated VIEs that are included in their respective captions above at March 31, 2023 and December 31, 2022, respectively. For further information, refer to Note 12.

[2] Fair value of $2 and $5 at March 31, 2023 and December 31, 2022, respectively.

[3] Includes $599 and $600 of residential mortgage loans held for sale measured at fair value at March 31, 2023 and December 31, 2022, respectively.