Fair Values - Financial Instruments Not Measured at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Financial Assets
Cash and due from banks	$ 35,721	$ 30,541	$ 36,641
Interest bearing deposits with banks	13,196	21,299	22,638
Restricted cash	30,739	35,356	$ 33,202
Securities borrowed	132,401	116,313
Customer and other receivables	59,514	53,298
Loans	110,815	99,815
Financial Liabilities
Deposits	180,738	187,820
Securities sold under agreements to repurchase	59,462	49,759
Securities loaned	9,691	11,908
Other secured financings	9,836	9,466
Customer and other payables	202,915	179,559
Borrowings	193,659	189,662
Carrying Value
Financial Assets
Cash and due from banks	35,721	30,541
Interest bearing deposits with banks	13,196	21,299
Restricted cash	30,739	35,356
Investment securities - HTM	41,076	30,771
Securities purchased under agreements to resell	93,363	98,522
Securities borrowed	132,401	116,313
Customer and other receivables	54,784	47,972
Loans	125,522	115,579
Other assets	474	461
Financial Liabilities
Deposits	179,116	187,378
Securities sold under agreements to repurchase	58,730	48,947
Securities loaned	9,691	11,908
Other secured financings	3,484	4,221
Customer and other payables	199,944	176,561
Borrowings	132,005	138,478
Additional Disclosures
Lending commitments	118,524	104,844
Fair Value
Financial Assets
Cash and due from banks	35,721	30,541
Interest bearing deposits with banks	13,196	21,299
Restricted cash	30,739	35,356
Investment securities - HTM	41,991	29,965
Securities purchased under agreements to resell	93,340	98,477
Securities borrowed	132,406	116,312
Customer and other receivables	54,735	47,839
Loans	125,522	115,725
Other assets	474	461
Financial Liabilities
Deposits	179,536	187,372
Securities sold under agreements to repurchase	58,724	48,910
Securities loaned	9,694	11,906
Other secured financings	3,488	4,227
Customer and other payables	199,944	176,561
Borrowings	135,419	140,115
Additional Disclosures
Lending commitments	1,237	1,570
Fair Value | Level 1
Financial Assets
Cash and due from banks	35,721	30,541
Interest bearing deposits with banks	13,196	21,299
Restricted cash	30,739	35,356
Investment securities - HTM	27,816	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	13,513	12,018
Securities purchased under agreements to resell	91,966	97,611
Securities borrowed	132,406	116,312
Customer and other receivables	51,855	44,620
Loans	23,119	25,604
Other assets	474	461
Financial Liabilities
Deposits	179,536	187,372
Securities sold under agreements to repurchase	58,724	48,385
Securities loaned	9,694	11,906
Other secured financings	3,488	3,233
Customer and other payables	199,944	176,561
Borrowings	135,409	140,085
Additional Disclosures
Lending commitments	889	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	662	474
Securities purchased under agreements to resell	1,374	866
Securities borrowed	0	0
Customer and other receivables	2,880	3,219
Loans	102,403	90,121
Other assets	0	0
Financial Liabilities
Deposits	0	0
Securities sold under agreements to repurchase	0	525
Securities loaned	0	0
Other secured financings	0	994
Customer and other payables	0	0
Borrowings	10	30
Additional Disclosures
Lending commitments	$ 348	$ 321