Segment, Geographic and Revenue Information - Selected Financial Information by Business Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information
Investment banking	$ 1,150	$ 2,560	$ 2,908	$ 5,400
Trading	3,597	3,330	7,580	7,555
Investments	23	381	98	699
Commissions and fees	1,220	1,308	2,636	2,934
Asset management	4,912	4,973	10,031	9,371
Other	(52)	342	182	626
Total non-interest revenues	10,850	12,894	23,435	26,585
Interest income	3,612	2,212	6,262	4,649
Interest expense	1,330	347	1,764	756
Net interest	2,282	1,865	4,498	3,893
Net revenues	13,132	14,759	27,933	30,478
Provision for credit losses	101	73	158	(25)
Compensation and benefits	5,550	6,423	11,824	13,221
Non-compensation expenses	4,162	3,697	8,044	7,372
Total non-interest expenses	9,712	10,120	19,868	20,593
Income before provision for income taxes	3,319	4,566	7,907	9,910
Provision for income taxes	783	1,054	1,656	2,230
Net income	2,536	3,512	6,251	7,680
Net income (loss) applicable to noncontrolling interests	41	1	90	49
Net income applicable to Morgan Stanley	2,495	3,511	6,161	7,631
I/E
Segment Reporting Information
Investment banking	(19)	(19)	(38)	(43)
Trading	15	19	33	42
Investments	0	0	0	0
Commissions and fees	(71)	(89)	(152)	(184)
Asset management	(57)	(40)	(99)	(75)
Other	(3)	(3)	(6)	(6)
Total non-interest revenues	(135)	(132)	(262)	(266)
Interest income	(188)	(37)	(244)	(64)
Interest expense	(189)	(39)	(246)	(69)
Net interest	1	2	2	5
Net revenues	(134)	(130)	(260)	(261)
Provision for credit losses	0	0	0	0
Compensation and benefits	0	0	0	0
Non-compensation expenses	(129)	(132)	(255)	(266)
Total non-interest expenses	(129)	(132)	(255)	(266)
Income before provision for income taxes	(5)	2	(5)	5
Provision for income taxes	(1)	0	(1)	1
Net income	(4)	2	(4)	4
Net income (loss) applicable to noncontrolling interests	0	0	0	0
Net income applicable to Morgan Stanley	(4)	2	(4)	4
IS | Operating Segments
Segment Reporting Information
Investment banking	1,072	2,376	2,706	4,989
Trading	3,976	3,078	8,181	7,151
Investments	(95)	61	4	147
Commissions and fees	688	682	1,462	1,552
Asset management	155	148	302	287
Other	(223)	137	(106)	295
Total non-interest revenues	5,573	6,482	12,549	14,421
Interest income	1,846	873	2,908	1,843
Interest expense	1,300	263	1,681	595
Net interest	546	610	1,227	1,248
Net revenues	6,119	7,092	13,776	15,669
Provision for credit losses	82	70	126	(23)
Compensation and benefits	2,050	2,433	4,654	5,547
Non-compensation expenses	2,433	2,091	4,655	4,276
Total non-interest expenses	4,483	4,524	9,309	9,823
Income before provision for income taxes	1,554	2,498	4,341	5,869
Provision for income taxes	395	574	930	1,310
Net income	1,159	1,924	3,411	4,559
Net income (loss) applicable to noncontrolling interests	38	20	99	54
Net income applicable to Morgan Stanley	1,121	1,904	3,312	4,505
WM | Operating Segments
Segment Reporting Information
Investment banking	97	203	240	454
Trading	(409)	255	(640)	381
Investments	15	14	27	16
Commissions and fees	603	714	1,326	1,565
Asset management	3,510	3,447	7,136	6,638
Other	173	207	295	360
Total non-interest revenues	3,989	4,840	8,384	9,414
Interest income	1,945	1,366	3,582	2,852
Interest expense	198	111	295	212
Net interest	1,747	1,255	3,287	2,640
Net revenues	5,736	6,095	11,671	12,054
Provision for credit losses	19	3	32	(2)
Compensation and benefits	2,895	3,275	6,020	6,445
Non-compensation expenses	1,301	1,181	2,525	2,375
Total non-interest expenses	4,196	4,456	8,545	8,820
Income before provision for income taxes	1,521	1,636	3,094	3,236
Provision for income taxes	331	372	632	730
Net income	1,190	1,264	2,462	2,506
Net income (loss) applicable to noncontrolling interests	0	0	0	0
Net income applicable to Morgan Stanley	1,190	1,264	2,462	2,506
IM | Operating Segments
Segment Reporting Information
Investment banking	0	0	0	0
Trading	15	(22)	6	(19)
Investments	103	306	67	536
Commissions and fees	0	1	0	1
Asset management	1,304	1,418	2,692	2,521
Other	1	1	(1)	(23)
Total non-interest revenues	1,423	1,704	2,764	3,016
Interest income	9	10	16	18
Interest expense	21	12	34	18
Net interest	(12)	(2)	(18)	0
Net revenues	1,411	1,702	2,746	3,016
Provision for credit losses	0	0	0	0
Compensation and benefits	605	715	1,150	1,229
Non-compensation expenses	557	557	1,119	987
Total non-interest expenses	1,162	1,272	2,269	2,216
Income before provision for income taxes	249	430	477	800
Provision for income taxes	58	108	95	189
Net income	191	322	382	611
Net income (loss) applicable to noncontrolling interests	3	(19)	(9)	(5)
Net income applicable to Morgan Stanley	$ 188	$ 341	$ 391	$ 616