Borrowings (Narrative) (Details) - USD ($)		6 Months Ended
		Jun. 30, 2023	Dec. 31, 2022
Line of Credit Facility [Line Items]
Other short-term borrowings outstanding	[1]	$ 7,831,000,000	$ 4,650,000,000
Weighted-average interest rate of short-term borrowings		5.01%	4.97%
Capacity of allowable commercial paper note issuance		$ 5,000,000,000
Commercial paper		0	$ 250,000,000
TDAC [Member]
Line of Credit Facility [Line Items]
Other short-term borrowings outstanding		$ 0	0
Commercial paper [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Maturity term		270 days
Federal Reserve Bank Advances [Member]
Line of Credit Facility [Line Items]
Other short-term borrowings outstanding		$ 0	0
Total borrowing capacity		8,800,000,000	7,800,000,000
Federal Reserve Bank Term Funding Program (BTFP) [Member]
Line of Credit Facility [Line Items]
Other short-term borrowings outstanding		0
Total borrowing capacity		41,600,000,000
Repurchase Agreements [Member]
Line of Credit Facility [Line Items]
Other short-term borrowings outstanding		7,800,000,000	4,400,000,000
Line of Credit [Member] | Uncommitted Lines Of Credit With External Banks [Member]
Line of Credit Facility [Line Items]
Other short-term borrowings outstanding		0	0
Total borrowing capacity		1,800,000,000
Line of Credit [Member] | Secured Uncommitted Lines Of Credit [Member]
Line of Credit Facility [Line Items]
Other short-term borrowings outstanding		0
Federal Home Loan Bank Advances [Member] | Secured Credit Facility [Member]
Line of Credit Facility [Line Items]
Borrowings outstanding		$ 41,000,000,000	$ 12,400,000,000
Weighted average interest rate		5.14%	4.88%
Total borrowing capacity		$ 38,300,000,000	$ 68,600,000,000

[1] Certain prior year amounts have been reclassified to conform to the current year presentation. See Note 1 for additional information.