Fair value measurement - Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Assets:
Interest-bearing deposits with the Federal Reserve and other central banks	$ 125,372	$ 102,467
Interest-bearing deposits with banks	16,639	16,630
Securities held-to-maturity	55,127	56,775
Other financial assets	1,268	1,187
Liabilities:
Noninterest-bearing deposits	106,060	93,695
Payables to customers and broker-dealers	25,769	25,150
Estimated fair value
Assets:
Interest-bearing deposits with the Federal Reserve and other central banks	125,372	102,467
Interest-bearing deposits with banks	16,645	16,636
Federal funds sold and securities purchased under resale agreements	22,940	29,607
Securities held-to-maturity	55,127	56,775
Loans	68,107	67,026
Other financial assets	6,669	7,300
Total assets	294,860	279,811
Liabilities:
Noninterest-bearing deposits	106,060	93,695
Interest-bearing deposits	216,221	224,665
Federal funds purchased and securities sold under repurchase agreements	11,434	11,566
Payables to customers and broker-dealers	25,769	25,150
Borrowings	768	956
Long-term debt	26,531	26,701
Total liabilities	386,783	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	11,823	12,488
Loans	0	0
Other financial assets	5,185	6,061
Total assets	17,008	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	125,372	102,467
Interest-bearing deposits with banks	16,645	16,636
Federal funds sold and securities purchased under resale agreements	22,940	29,607
Securities held-to-maturity	43,304	44,287
Loans	68,107	67,026
Other financial assets	1,484	1,239
Total assets	277,852	261,262
Liabilities:
Noninterest-bearing deposits	106,060	93,695
Interest-bearing deposits	216,221	224,665
Federal funds purchased and securities sold under repurchase agreements	11,434	11,566
Payables to customers and broker-dealers	25,769	25,150
Borrowings	768	956
Long-term debt	26,531	26,701
Total liabilities	386,783	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	125,372	102,467
Interest-bearing deposits with banks	16,639	16,630
Federal funds sold and securities purchased under resale agreements	22,940	29,607
Securities held-to-maturity	59,566	56,866
Loans	68,464	66,860
Other financial assets	6,669	7,300
Total assets	299,650	279,730
Liabilities:
Noninterest-bearing deposits	106,060	93,695
Interest-bearing deposits	219,753	225,999
Federal funds purchased and securities sold under repurchase agreements	11,434	11,566
Payables to customers and broker-dealers	25,769	25,150
Borrowings	768	956
Long-term debt	27,610	25,931
Total liabilities	$ 391,394	$ 383,297