Customer Contract Revenue Recognition (Customer Contract Renenues) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Disaggregation of Revenue
Revenues from contracts with customers	$ 5,910
Revenue recognized from services performed over multiple periods	902
Americas
Disaggregation of Revenue
Revenues from contracts with customers	4,738
EMEA
Disaggregation of Revenue
Revenues from contracts with customers	622
Asia
Disaggregation of Revenue
Revenues from contracts with customers	550
I/E
Disaggregation of Revenue
Revenues from contracts with customers	(129)
IS
Disaggregation of Revenue
Revenues from contracts with customers	2,221
WM
Disaggregation of Revenue
Revenues from contracts with customers	3,192
IM
Disaggregation of Revenue
Revenues from contracts with customers	626
Investment Banking
Disaggregation of Revenue
Revenues from contracts with customers	1,429
Investment Banking | I/E
Disaggregation of Revenue
Revenues from contracts with customers	(19)
Investment Banking | IS
Disaggregation of Revenue
Revenues from contracts with customers	1,308
Investment Banking | WM
Disaggregation of Revenue
Revenues from contracts with customers	140
Investment Banking | IM
Disaggregation of Revenue
Revenues from contracts with customers	0
Commissions and Fees
Disaggregation of Revenue
Revenues from contracts with customers	1,173
Commissions and Fees | I/E
Disaggregation of Revenue
Revenues from contracts with customers	(69)
Commissions and Fees | IS
Disaggregation of Revenue
Revenues from contracts with customers	744
Commissions and Fees | WM
Disaggregation of Revenue
Revenues from contracts with customers	498
Commissions and Fees | IM
Disaggregation of Revenue
Revenues from contracts with customers	0
Asset Management
Disaggregation of Revenue
Revenues from contracts with customers	3,192
Asset Management | I/E
Disaggregation of Revenue
Revenues from contracts with customers	(39)
Asset Management | IS
Disaggregation of Revenue
Revenues from contracts with customers	110
Asset Management | WM
Disaggregation of Revenue
Revenues from contracts with customers	2,495
Asset Management | IM
Disaggregation of Revenue
Revenues from contracts with customers	626
Ohter Customer Contract Revenues
Disaggregation of Revenue
Revenues from contracts with customers	116
Ohter Customer Contract Revenues | I/E
Disaggregation of Revenue
Revenues from contracts with customers	(2)
Ohter Customer Contract Revenues | IS
Disaggregation of Revenue
Revenues from contracts with customers	59
Ohter Customer Contract Revenues | WM
Disaggregation of Revenue
Revenues from contracts with customers	59
Ohter Customer Contract Revenues | IM
Disaggregation of Revenue
Revenues from contracts with customers	$ 0