Related Party Transactions - Summary of Related Party Transactions (Details) - USD ($) $ in Millions		Sep. 30, 2020		Dec. 31, 2019		Sep. 30, 2019
Assets:
Cash and due from banks		$ 1,352		$ 1,744
Interest bearing deposits with banks		16,126		2,038
Securities purchased under agreements to resell		25,579		17,838
Trading assets		33,754		28,452
Loans		66,409		68,553
Other		6,370		6,723
Total assets		200,946	[1]	175,375	[1]	$ 184,760
Liabilities:
Deposits		150,328		119,693		$ 119,801
Trading liabilities		3,517		3,235
Short-term borrowings		5,515		3,659
Long-term debt		20,048		26,697
Other		3,198		3,835
Total liabilities	[1]	182,606		157,119
Affiliated Entity [Member]
Assets:
Cash and due from banks		677		850
Interest bearing deposits with banks		26		40
Securities purchased under agreements to resell	[2]	2,185		4,600
Trading assets		470		79
Loans		1,180		2,343
Other	[2]	360		456
Total assets		4,898		8,368
Liabilities:
Deposits		18,397		9,000
Trading liabilities		324		293
Short-term borrowings		949		1,166
Long-term debt		2,866		7,848
Other	[2]	194		931
Total liabilities		$ 22,730		$ 19,238

[1] Assets

[2] Other assets and other liabilities primarily consist of derivative balances associated with hedging activities and other miscellaneous account receivables and payables.