Collateralized Transactions - Offsetting of Certain Collateralized Transactions (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Securities purchased under agreements to resell
Gross amounts	$ 263,485	$ 262,976
Amounts offset	(170,118)	(164,454)
Net amounts presented	93,367	98,522
Amounts not offset	(91,505)	(95,610)
Net amounts	1,862	2,912
Securities borrowed
Gross amounts	142,723	134,711
Amounts offset	(10,322)	(18,398)
Net amounts presented	132,401	116,313
Amounts not offset	(126,161)	(112,551)
Net amounts	6,240	3,762
Securities sold under agreements to repurchase
Gross amounts	229,626	214,213
Amounts offset	(170,164)	(164,454)
Net amounts presented	59,462	49,759
Amounts not offset	(42,091)	(41,095)
Net amounts	17,371	8,664
Securities loaned
Gross amounts	19,967	30,306
Amounts offset	(10,276)	(18,398)
Net amounts presented	9,691	11,908
Amounts not offset	(9,660)	(11,677)
Net amounts	31	231
Net amounts for which master netting agreements are not in place or may not be legally enforceable
Securities purchased under agreements to resell	1,390	2,579
Securities borrowed	1,578	724
Securities sold under agreements to repurchase	15,695	6,762
Securities loaned	$ 20	$ 191