Earnings Per Common Share (Calculation of Basic and Diluted EPS) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Basic EPS
Income from continuing operations	$ 1,680	$ 1,632	$ 1,650	$ 1,160	$ 943	$ 1,051	$ 1,833	$ 2,468	$ 6,122	$ 6,295	$ 3,681
Income (loss) from discontinued operations	0	8	(4)	(3)	(7)	(2)	(2)	(5)	1	(16)	(14)
Net income	1,680	1,640	1,646	1,157	936	1,049	1,831	2,463	6,123	6,279	3,667
Net income applicable to noncontrolling interests	14	43	64	23	28	31	24	69	144	152	200
Net income applicable to Morgan Stanley	1,666	1,597	1,582	1,134	908	1,018	1,807	2,394	5,979	6,127	3,467
Less: Preferred stock dividends									(468)	(452)	(311)
Less: Allocation of (earnings) loss to participating RSUs									(3)	(4)	(4)
Earnings applicable to Morgan Stanley common shareholders	$ 1,510	$ 1,518	$ 1,425	$ 1,055	$ 753	$ 939	$ 1,665	$ 2,314	$ 5,508	$ 5,671	$ 3,152
Weighted average common shares outstanding									1,849	1,909	1,924
Earnings per basic common share
Income from continuing operations	$ 0.84	$ 0.82	$ 0.77	$ 0.56	$ 0.4	$ 0.49	$ 0.87	$ 1.21	$ 2.98	$ 2.98	$ 1.65
Income (loss) from discontinued operations	0	0.01	(0.01)	0	0	0	0	(0.01)	0	(0.01)	(0.01)
Earnings per basic common share	$ 0.84	$ 0.83	$ 0.76	$ 0.56	$ 0.4	$ 0.49	$ 0.87	$ 1.2	$ 2.98	$ 2.97	$ 1.64
Diluted EPS
Earnings applicable to Morgan Stanley common shareholders	$ 1,510	$ 1,518	$ 1,425	$ 1,055	$ 753	$ 939	$ 1,665	$ 2,314	$ 5,508	$ 5,671	$ 3,152
Weighted average common shares outstanding									1,849	1,909	1,924
Effect of dilutive securities:
Stock options and RSUs									38	44	47
Weighted average common shares outstanding and common stock equivalents									1,887	1,953	1,971
Earnings per diluted common share
Income from continuing operations	$ 0.81	$ 0.8	$ 0.75	$ 0.55	$ 0.39	$ 0.48	$ 0.85	$ 1.18	$ 2.92	$ 2.91	$ 1.61
Income (loss) from discontinued operations	0	0.01	0	0	0	0	0	0	0	(0.01)	(0.01)
Earnings per diluted common share	$ 0.81	$ 0.81	$ 0.75	$ 0.55	$ 0.39	$ 0.48	$ 0.85	$ 1.18	$ 2.92	$ 2.9	$ 1.6
Antidilutive securities excluded from EPS computations									13	12	15