Fair value measurement - Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Assets:
Interest-bearing deposits with the Federal Reserve and other central banks	$ 107,427	$ 102,467
Interest-bearing deposits with banks	13,890	16,630
Securities held-to-maturity	50,485	56,775
Other financial assets	1,599	1,187
Liabilities:
Noninterest-bearing deposits	88,275	93,695
Payables to customers and broker-dealers	23,741	25,150
Estimated fair value
Assets:
Interest-bearing deposits with the Federal Reserve and other central banks	107,427	102,467
Interest-bearing deposits with banks	13,887	16,636
Federal funds sold and securities purchased under resale agreements	23,483	29,607
Securities held-to-maturity	50,485	56,775
Loans	68,585	67,026
Other financial assets	6,378	7,300
Total assets	270,245	279,811
Liabilities:
Noninterest-bearing deposits	88,275	93,695
Interest-bearing deposits	208,794	224,665
Federal funds purchased and securities sold under repurchase agreements	11,339	11,566
Payables to customers and broker-dealers	23,741	25,150
Borrowings	683	956
Long-term debt	25,975	26,701
Total liabilities	358,807	382,733
Estimated fair value | Level 1
Assets:
Interest-bearing deposits with the Federal Reserve and other central banks	0	0
Interest-bearing deposits with banks	0	0
Federal funds sold and securities purchased under resale agreements	0	0
Securities held-to-maturity	10,750	12,488
Loans	0	0
Other financial assets	4,707	6,061
Total assets	15,457	18,549
Liabilities:
Noninterest-bearing deposits	0	0
Interest-bearing deposits	0	0
Federal funds purchased and securities sold under repurchase agreements	0	0
Payables to customers and broker-dealers	0	0
Borrowings	0	0
Long-term debt	0	0
Total liabilities	0	0
Estimated fair value | Level 2
Assets:
Interest-bearing deposits with the Federal Reserve and other central banks	107,427	102,467
Interest-bearing deposits with banks	13,887	16,636
Federal funds sold and securities purchased under resale agreements	23,483	29,607
Securities held-to-maturity	39,735	44,287
Loans	68,585	67,026
Other financial assets	1,671	1,239
Total assets	254,788	261,262
Liabilities:
Noninterest-bearing deposits	88,275	93,695
Interest-bearing deposits	208,794	224,665
Federal funds purchased and securities sold under repurchase agreements	11,339	11,566
Payables to customers and broker-dealers	23,741	25,150
Borrowings	683	956
Long-term debt	25,975	26,701
Total liabilities	358,807	382,733
Estimated fair value | Level 3
Assets:
Interest-bearing deposits with the Federal Reserve and other central banks	0	0
Interest-bearing deposits with banks	0	0
Federal funds sold and securities purchased under resale agreements	0	0
Securities held-to-maturity	0	0
Loans	0	0
Other financial assets	0	0
Total assets	0	0
Liabilities:
Noninterest-bearing deposits	0	0
Interest-bearing deposits	0	0
Federal funds purchased and securities sold under repurchase agreements	0	0
Payables to customers and broker-dealers	0	0
Borrowings	0	0
Long-term debt	0	0
Total liabilities	0	0
Carrying amount
Assets:
Interest-bearing deposits with the Federal Reserve and other central banks	107,427	102,467
Interest-bearing deposits with banks	13,890	16,630
Federal funds sold and securities purchased under resale agreements	23,483	29,607
Securities held-to-maturity	57,257	56,866
Loans	68,963	66,860
Other financial assets	6,378	7,300
Total assets	277,398	279,730
Liabilities:
Noninterest-bearing deposits	88,275	93,695
Interest-bearing deposits	213,714	225,999
Federal funds purchased and securities sold under repurchase agreements	11,339	11,566
Payables to customers and broker-dealers	23,741	25,150
Borrowings	683	956
Long-term debt	27,820	25,931
Total liabilities	$ 365,572	$ 383,297