Lines of business - Contribution of Segments to Overall Profitability (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020		Dec. 31, 2019	Mar. 31, 2019
Segment Reporting Information [Line Items]
Total fee and other revenue		$ 3,332		$ 3,946	$ 3,032
Net interest revenue (expense)		814		815	841
Provision for credit losses	[2]	169	[1]	(8)	7	[1]
Income from consolidated investment management funds, net of noncontrolling interests		980		1,440	946
Investment income (loss), net		(38)		17	26
Net income (loss) attributable to noncontrolling interests		(18)		9	10
Investment Management
Segment Reporting Information [Line Items]
Net income (loss) attributable to noncontrolling interests		(18)		9	10
Operating segments
Segment Reporting Information [Line Items]
Total fee and other revenue		3,312		3,954	3,048
Net interest revenue (expense)		814		815	841
Total revenue		4,126		4,769	3,889
Provision for credit losses		169		(8)	7
Noninterest expense		2,712		2,964	2,699
Income (loss) before taxes		$ 1,245		$ 1,813	$ 1,183
Pre-tax operating margin		30.00%		38.00%	31.00%
Average assets		$ 385,278		$ 354,341	$ 336,165
Operating segments | Investment Services
Segment Reporting Information [Line Items]
Total fee and other revenue		2,436		2,236	2,161
Net interest revenue (expense)		806		778	804
Total revenue		3,242		3,014	2,965
Provision for credit losses		149		(5)	8
Noninterest expense		1,987		2,179	1,981
Income (loss) before taxes		$ 1,106		$ 840	$ 976
Pre-tax operating margin		34.00%		28.00%	33.00%
Average assets		$ 304,089		$ 278,098	$ 256,034
Operating segments | Investment Management
Segment Reporting Information [Line Items]
Total fee and other revenue		846		924	869
Net interest revenue (expense)		52		47	67
Total revenue		898		971	936
Provision for credit losses		9		0	1
Noninterest expense		695		731	669
Income (loss) before taxes		$ 194		$ 240	$ 266
Pre-tax operating margin		22.00%		25.00%	28.00%
Average assets		$ 30,543		$ 28,481	$ 31,857
Income from consolidated investment management funds, net of noncontrolling interests		(20)		8	16
Investment income (loss), net		(38)		17	26
Net income (loss) attributable to noncontrolling interests		(18)		9	10
Operating segments | Other
Segment Reporting Information [Line Items]
Total fee and other revenue		30		794	18
Net interest revenue (expense)		(44)		(10)	(30)
Total revenue		(14)		784	(12)
Provision for credit losses		11		(3)	(2)
Noninterest expense		30		54	49
Income (loss) before taxes		(55)		733	(59)
Average assets		$ 50,646		$ 47,762	$ 48,274

[1] In the first quarter of 2020, we adopted new accounting guidance included in ASU 2016-13, Financial Instruments - Credit Losses: Measurement of Credit Losses On Financial Instruments, on a prospective basis. See Note 2 of the Notes to Consolidated Financial Statements for additional information.

[2] The provision for credit losses for the quarter ended March 31, 2020 relates to the financial instruments within the scope of Accounting Standards Update (“ASU”) 2016-13, Financial Instruments - Credit Losses: Measurement of Credit Losses On Financial Instruments. See Note 2 of the Notes to Consolidated Financial Statements for additional information.