Employee Benefit Plans Employee Benefit Plans (Net Periodic Defined Benefit Cost) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020		Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Net periodic defined benefit (credit) cost		$ (81)	$ (55)		$ (35)
Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	38	32	[2]	31	[2]
Interest cost		61	70	[2]	80	[2]
Expected return on plan assets		(202)	(185)	[2]	(172)	[2]
Amortization of prior service credit		(19)	(19)	[2]	(19)	[2]
Amortization of actuarial net loss		29	38	[2]	34	[2]
Total other components of net benefit (credit) cost	[3]	(131)	(96)	[2]	(77)	[2]
Net periodic defined benefit (credit) cost		(93)	(64)	[2]	(46)	[2]
Actual return on plan assets		$ 291	$ 537	[2]	$ 579	[2]
Actual rate of return on plan assets, percent		8.92%	18.72%	[2]	24.07%	[2]
Weighted-average assumptions, discount rate, percent		2.71%	3.43%	[2]	4.37%	[2]
Weighted-average assumptions, expected long-term return on plan assets, percent		6.50%	6.50%	[2]	6.50%	[2]
Weighted-average assumptions, rate of compensation increase, percent		4.00%	4.00%	[2]	4.00%	[2]
Non-Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	$ 2	$ 1		$ 3
Interest cost		7	8		9
Expected return on plan assets		0	0		0
Amortization of prior service credit		(6)	(8)		(8)
Amortization of actuarial net loss		11	9		7
Total other components of net benefit (credit) cost	[3]	12	9		8
Net periodic defined benefit (credit) cost		$ 14	$ 10		$ 11
Weighted-average assumptions, discount rate, percent		2.71%	3.43%		4.37%
Weighted-average assumptions, rate of compensation increase, percent		4.00%	4.00%		4.00%
Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 0	$ 0
Interest cost		1	1		$ 2
Expected return on plan assets		(3)	(2)		(3)
Amortization of actuarial net loss		0	0		1
Net periodic defined benefit (credit) cost		(2)	(1)		0
Actual return on plan assets		$ (1)	$ 3		$ 5
Actual rate of return on plan assets, percent		(2.25%)	6.00%		9.14%
Weighted-average assumptions, discount rate, percent		2.43%	3.26%		4.26%
Weighted-average assumptions, expected long-term return on plan assets, percent		5.00%	5.00%		5.00%
Health care cost trend rate assumed		6.00%	6.25%		6.50%
Rate to which the healthcare cost trend rate is assumed to decline (the ultimate trend rate), percent		4.50%	4.50%		4.50%
Defined Benefit Plan Year That Reaches Ultimate Trend Rate In Current Expense		2027	2027		2027

[1] Included in salaries and benefits expense on the Consolidated Statements of Income.

[2] Recast to reflect the retrospective application of the Corporation's election to change the accounting method for certain components of defined pension benefit credit, effective January 1, 2021. For 2020, expected return on plan assets increased $14 million and amortization of net loss was reduced by $16 million, resulting in an increase of $30 million to total other components of net benefit credit. For 2019, expected return on plan assets increased $6 million, resulting in a corresponding increase to total other components of net benefit credit.

[3] Included in other noninterest expenses on the Consolidated Statements of Income.