Segment, Geographic and Revenue Information - Selected Financial Information by Business Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information
Investment banking	$ 1,758	$ 2,840
Trading	3,983	4,225
Investments	75	318
Commissions and fees	1,416	1,626
Asset management	5,119	4,398
Other	234	284
Total non-interest revenues	12,585	13,691
Interest income	2,650	2,437
Interest expense	434	409
Net interest	2,216	2,028
Net revenues	14,801	15,719
Provision for credit losses	57	(98)
Compensation and benefits	6,274	6,798
Non-compensation expenses	3,882	3,675
Total non-interest expenses	10,156	10,473
Income before provision for income taxes	4,588	5,344
Provision for income taxes	873	1,176
Net income	3,715	4,168
Net income (loss) applicable to noncontrolling interests	49	48
Net income applicable to Morgan Stanley	3,666	4,120
I/E
Segment Reporting Information
Investment banking	(19)	(24)
Trading	18	23
Investments	0	0
Commissions and fees	(81)	(95)
Asset management	(42)	(35)
Other	(3)	(3)
Total non-interest revenues	(127)	(134)
Interest income	(56)	(27)
Interest expense	(57)	(30)
Net interest	1	3
Net revenues	(126)	(131)
Provision for credit losses	0	0
Compensation and benefits	0	0
Non-compensation expenses	(126)	(134)
Total non-interest expenses	(126)	(134)
Income before provision for income taxes	0	3
Provision for income taxes	0	1
Net income	0	2
Net income (loss) applicable to noncontrolling interests	0	0
Net income applicable to Morgan Stanley	0	2
IS | Operating Segments
Segment Reporting Information
Investment banking	1,634	2,613
Trading	4,205	4,073
Investments	99	86
Commissions and fees	774	870
Asset management	147	139
Other	117	158
Total non-interest revenues	6,976	7,939
Interest income	1,062	970
Interest expense	381	332
Net interest	681	638
Net revenues	7,657	8,577
Provision for credit losses	44	(93)
Compensation and benefits	2,604	3,114
Non-compensation expenses	2,222	2,185
Total non-interest expenses	4,826	5,299
Income before provision for income taxes	2,787	3,371
Provision for income taxes	535	736
Net income	2,252	2,635
Net income (loss) applicable to noncontrolling interests	61	34
Net income applicable to Morgan Stanley	2,191	2,601
WM | Operating Segments
Segment Reporting Information
Investment banking	143	251
Trading	(231)	126
Investments	12	2
Commissions and fees	723	851
Asset management	3,626	3,191
Other	122	153
Total non-interest revenues	4,395	4,574
Interest income	1,637	1,486
Interest expense	97	101
Net interest	1,540	1,385
Net revenues	5,935	5,959
Provision for credit losses	13	(5)
Compensation and benefits	3,125	3,170
Non-compensation expenses	1,224	1,194
Total non-interest expenses	4,349	4,364
Income before provision for income taxes	1,573	1,600
Provision for income taxes	301	358
Net income	1,272	1,242
Net income (loss) applicable to noncontrolling interests	0	0
Net income applicable to Morgan Stanley	1,272	1,242
IM | Operating Segments
Segment Reporting Information
Investment banking	0	0
Trading	(9)	3
Investments	(36)	230
Commissions and fees	0	0
Asset management	1,388	1,103
Other	(2)	(24)
Total non-interest revenues	1,341	1,312
Interest income	7	8
Interest expense	13	6
Net interest	(6)	2
Net revenues	1,335	1,314
Provision for credit losses	0	0
Compensation and benefits	545	514
Non-compensation expenses	562	430
Total non-interest expenses	1,107	944
Income before provision for income taxes	228	370
Provision for income taxes	37	81
Net income	191	289
Net income (loss) applicable to noncontrolling interests	(12)	14
Net income applicable to Morgan Stanley	$ 203	$ 275