Fair Values - Financial Instruments Not Measured at Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Financial Assets
Cash and due from banks	$ 38,257	$ 30,541	$ 30,176
Interest bearing deposits with banks	10,888	21,299	18,707
Restricted cash	30,435	35,356	$ 32,706
Securities borrowed	133,580	116,313
Customer and other receivables	53,381	53,298
Loans	105,145	99,815
Financial Liabilities
Deposits	176,593	187,820
Securities sold under agreements to repurchase	62,294	49,759
Securities loaned	10,325	11,908
Other secured financings	11,981	9,466
Customer and other payables	192,098	179,559
Borrowings	197,848	189,662
Carrying Value
Financial Assets
Cash and due from banks	38,257	30,541
Interest bearing deposits with banks	10,888	21,299
Restricted cash	30,435	35,356
Investment securities - HTM	40,028	30,771
Securities purchased under agreements to resell	85,394	98,522
Securities borrowed	133,580	116,313
Customer and other receivables	48,423	47,972
Loans	120,901	115,579
Other assets	461	461
Financial Liabilities
Deposits	175,659	187,378
Securities sold under agreements to repurchase	61,636	48,947
Securities loaned	10,325	11,908
Other secured financings	3,505	4,221
Customer and other payables	188,622	176,561
Borrowings	136,339	138,478
Additional Disclosures
Lending commitments	125,417	104,844
Fair Value
Financial Assets
Cash and due from banks	38,257	30,541
Interest bearing deposits with banks	10,888	21,299
Restricted cash	30,435	35,356
Investment securities - HTM	40,519	29,965
Securities purchased under agreements to resell	85,461	98,477
Securities borrowed	133,581	116,312
Customer and other receivables	48,356	47,839
Loans	121,224	115,725
Other assets	461	461
Financial Liabilities
Deposits	175,954	187,372
Securities sold under agreements to repurchase	61,608	48,910
Securities loaned	10,324	11,906
Other secured financings	3,508	4,227
Customer and other payables	188,622	176,561
Borrowings	140,523	140,115
Additional Disclosures
Lending commitments	1,244	1,570
Fair Value | Level 1
Financial Assets
Cash and due from banks	38,257	30,541
Interest bearing deposits with banks	10,888	21,299
Restricted cash	30,435	35,356
Investment securities - HTM	25,672	17,473
Securities purchased under agreements to resell	0	0
Securities borrowed	0	0
Customer and other receivables	0	0
Loans	0	0
Other assets	0	0
Financial Liabilities
Deposits	0	0
Securities sold under agreements to repurchase	0	0
Securities loaned	0	0
Other secured financings	0	0
Customer and other payables	0	0
Borrowings	0	0
Additional Disclosures
Lending commitments	0	0
Fair Value | Level 2
Financial Assets
Cash and due from banks	0	0
Interest bearing deposits with banks	0	0
Restricted cash	0	0
Investment securities - HTM	14,243	12,018
Securities purchased under agreements to resell	84,026	97,611
Securities borrowed	133,581	116,312
Customer and other receivables	45,511	44,620
Loans	22,661	25,604
Other assets	461	461
Financial Liabilities
Deposits	175,954	187,372
Securities sold under agreements to repurchase	61,083	48,385
Securities loaned	10,324	11,906
Other secured financings	3,508	3,233
Customer and other payables	188,622	176,561
Borrowings	140,512	140,085
Additional Disclosures
Lending commitments	919	1,249
Fair Value | Level 3
Financial Assets
Cash and due from banks	0	0
Interest bearing deposits with banks	0	0
Restricted cash	0	0
Investment securities - HTM	604	474
Securities purchased under agreements to resell	1,435	866
Securities borrowed	0	0
Customer and other receivables	2,845	3,219
Loans	98,563	90,121
Other assets	0	0
Financial Liabilities
Deposits	0	0
Securities sold under agreements to repurchase	525	525
Securities loaned	0	0
Other secured financings	0	994
Customer and other payables	0	0
Borrowings	11	30
Additional Disclosures
Lending commitments	$ 325	$ 321