Parent Company (Condensed Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Assets
Cash and due from banks	$ 22,017	$ 19,827	$ 19,827	$ 21,381
Interest bearing deposits with banks	21,364	34,256	$ 34,256	25,603
Trading assets, at fair value	262,154	239,505
Equity investment in subsidiaries:
Other assets	52,125	51,087
Total assets	814,949	787,465
Liabilities
Short-term borrowings	941	2,173
Trading liabilities, at fair value	128,194	128,455
Other liabilities and accrued expenses	15,896	18,711
Long-term borrowings	164,775	153,768
Total liabilities	737,772	711,281
Commitments and contingent liabilities
Equity
Preferred stock	7,520	7,520
Common stock, $0.01 par value: Shares authorized: 3,500,000,000; Shares issued: 2,038,893,979; Shares outstanding: 1,852,481,601 and 1,920,024,027	20	20
Additional paid-in capital	23,271	24,153
Retained earnings	53,679	49,204
Employee stock trusts	2,851	2,409
Common stock held in treasury, at cost, $0.01 par value (186,412,378 and 118,869,952 shares)	(5,797)	(4,059)
Common stock issued to employee stock trusts	(2,851)	(2,409)
Total Morgan Stanley shareholders' equity	76,050	75,182
Total liabilities and equity	814,949	787,465
Parent Company
Assets
Cash and due from banks	119	5,169		5,068
Deposits with banking subsidiaries	3,600	4,311		4,556
Interest bearing deposits with banks	0	2,421		$ 1,126
Trading assets, at fair value	139	354
Securities purchased under agreement to resell with affiliate	57,906	47,060
Advances to subsidiaries:
Bank and bank holding company	28,186	18,380
Non-bank	95,684	106,192
Equity investment in subsidiaries:
Bank and bank holding company	34,329	25,787
Non-bank	31,246	34,927
Other assets	4,613	6,259
Total assets	255,822	250,860
Liabilities
Short-term borrowings	1	40
Trading liabilities, at fair value	49	138
Payables to subsidiaries	26,957	29,220
Other liabilities and accrued expenses	2,040	2,189
Long-term borrowings	150,725	144,091
Total liabilities	179,772	175,678
Commitments and contingent liabilities
Equity
Preferred stock	7,520	7,520
Common stock, $0.01 par value: Shares authorized: 3,500,000,000; Shares issued: 2,038,893,979; Shares outstanding: 1,852,481,601 and 1,920,024,027	20	20
Additional paid-in capital	23,271	24,153
Retained earnings	53,679	49,204
Employee stock trusts	2,851	2,409
Accumulated other comprehensive income (loss)	(2,643)	(1,656)
Common stock held in treasury, at cost, $0.01 par value (186,412,378 and 118,869,952 shares)	(5,797)	(4,059)
Common stock issued to employee stock trusts	(2,851)	(2,409)
Total Morgan Stanley shareholders' equity	76,050	75,182
Total liabilities and equity	$ 255,822	$ 250,860