Fair Value Measurements - Carrying Amounts and Estimated Fair Values for Certain Financial Instruments (Details) - USD ($) $ in Millions		Mar. 31, 2022	Dec. 31, 2021
Financial assets:
Cash and due from banks		$ 3,049	$ 2,994
Other short-term investments	[1]	20,529	34,572
Held-to-maturity securities		6	8
Loans and leases held for sale	[2]	2,616	4,415
Total portfolio loans and leases, net		113,957	110,158
Financial liabilities:
Deposits		170,611	169,324
Federal funds purchased		250	281
Other short-term borrowings		872	980
Long-term debt	[1]	10,815	11,821
Commercial
Financial assets:
Total portfolio loans and leases, net		72,938	70,268
Consumer
Financial assets:
Total portfolio loans and leases, net		42,927	41,782
Net Carrying Amount
Financial assets:
Cash and due from banks		3,049	2,994
Other short-term investments		20,529	34,572
Other securities		518	519
Held-to-maturity securities		6	8
Loans and leases held for sale		1,758	3,392
Total portfolio loans and leases, net		113,812	110,004
Financial liabilities:
Deposits		170,611	169,324
Federal funds purchased		250	281
Other short-term borrowings		872	980
Long-term debt		10,571	11,425
Net Carrying Amount | Commercial
Financial assets:
Total portfolio loans and leases, net		71,828	69,166
Net Carrying Amount | Consumer
Financial assets:
Total portfolio loans and leases, net		41,984	40,838
Total Fair Value
Financial assets:
Cash and due from banks		3,049	2,994
Other short-term investments		20,529	34,572
Other securities		518	519
Held-to-maturity securities		6	8
Loans and leases held for sale		1,767	3,405
Total portfolio loans and leases, net		113,955	111,556
Financial liabilities:
Deposits		170,585	169,316
Federal funds purchased		250	281
Other short-term borrowings		872	980
Long-term debt		11,035	12,478
Total Fair Value | Commercial
Financial assets:
Total portfolio loans and leases, net		72,153	69,924
Total Fair Value | Consumer
Financial assets:
Total portfolio loans and leases, net		41,802	41,632
Total Fair Value | Level 1
Financial assets:
Cash and due from banks		3,049	2,994
Other short-term investments		20,529	34,572
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		250	281
Other short-term borrowings		0	0
Long-term debt		10,659	12,091
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		518	519
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		170,585	169,316
Federal funds purchased		0	0
Other short-term borrowings		872	980
Long-term debt		376	387
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		6	8
Loans and leases held for sale		1,767	3,405
Total portfolio loans and leases, net		113,955	111,556
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		72,153	69,924
Total Fair Value | Level 3 | Consumer
Financial assets:
Total portfolio loans and leases, net		$ 41,802	$ 41,632

[1] Includes $24 and $24 of other short-term investments, $266 and $322 of portfolio loans and leases, $(2) and $(2) of ALLL, $2 and $2 of other assets, an immaterial amount and $1 of other liabilities, and $209 and $263 of long-term debt from consolidated VIEs that are included in their respective captions above at March 31, 2022 and December 31, 2021, respectively. For further information, refer to Note 11.

[2] Includes $858 and $1,023 of residential mortgage loans held for sale measured at fair value at March 31, 2022 and December 31, 2021, respectively.