Commitments, Guarantees and Contingencies (Contingencies) (Details) - 3 months ended Mar. 31, 2018 - Pending Litigation € in Millions, $ in Millions	EUR (€)	USD ($)
China Development Industrial Bank v. Morgan Stanley & Co. Incorporated et al.
Loss Contingencies
Lawsuit filing date	Jul. 15, 2010
Name of plaintiff	China Development Industrial Bank (“CDIB”)
Name of defendant	The Firm
Domicile of litigation	The Supreme Court of the State of New York, New York County (“Supreme Court of NY”)
Allegations	The complaint relates to a $275 million CDS referencing the super senior portion of the STACK 2006-1 CDO. The complaint asserts claims for common law fraud, fraudulent inducement and fraudulent concealment and alleges that the Firm misrepresented the risks of the STACK 2006-1 CDO to CDIB, and that the Firm knew that the assets backing the CDO were of poor quality when it entered into the CDS with CDIB.
Damages sought	The complaint seeks compensatory damages related to the approximately $228 million that CDIB alleges it has already lost under the CDS, rescission of CDIB’s obligation to pay an additional $12 million, punitive damages, equitable relief, fees and costs.
China Development Industrial Bank v. Morgan Stanley & Co. Incorporated et al. | Maximum
Loss Contingencies
Estimate of possible loss		$ 240
Deutsche Zentral-Genossenschaftsbank AG et al. v. Morgan Stanley et al.
Loss Contingencies
Lawsuit filing date	May 03, 2013
Name of defendant	The Firm
Domicile of litigation	The Supreme Court of NY
Allegations	The complaint alleges that defendants made material misrepresentations and omissions in the sale to plaintiffs of certain mortgage pass-through certificates backed by securitization trusts containing residential mortgage loans. The total amount of certificates allegedly sponsored, underwritten and/or sold by the Firm to plaintiff was approximately $634 million. The complaint alleges causes of action against the Firm for common law fraud, fraudulent concealment, aiding and abetting fraud, negligent misrepresentation, and rescission.
Damages sought	The complaint seeks, among other things, compensatory and punitive damages.
Request for information	At March 25, 2018, the current unpaid balance of the mortgage pass-through certificates at issue in this action was approximately $211 million, and the certificates had incurred actual losses of approximately $89 million.
US Bank National Association, solely in its capacity as Trustee of the Morgan Stanley Mortgage Loan Trust 2007-2AX (MSM 2007-2AX) v. Morgan Stanley Mortgage Capital Holdings LLC, as Successor-by-Merger to Morgan Stanley Mortgage Capital Inc. and GreenPoint Mortgage Funding, Inc.
Loss Contingencies
Lawsuit filing date	Jul. 08, 2013
Name of plaintiff	U.S. Bank National Association
Name of defendant	The Firm
Domicile of litigation	The Supreme Court of NY
Allegations	The complaint asserts claims for breach of contract and alleges, among other things, that the loans in the trust, which had an original principal balance of approximately $650 million, breached various representations and warranties.
Damages sought	The complaint seeks, among other relief, specific performance of the loan breach remedy procedures in the transaction documents, unspecified damages and interest.
US Bank National Association, solely in its capacity as Trustee of the Morgan Stanley Mortgage Loan Trust 2007-2AX (MSM 2007-2AX) v. Morgan Stanley Mortgage Capital Holdings LLC, as Successor-by-Merger to Morgan Stanley Mortgage Capital Inc. and GreenPoint Mortgage Funding, Inc. | Maximum
Loss Contingencies
Estimate of possible loss		240
Wilmington Trust Company v. Morgan Stanley Mortgage Capital Holdings LLC et al.
Loss Contingencies
Lawsuit filing date	Dec. 30, 2013
Name of plaintiff	Wilmington Trust Company
Name of defendant	The Firm
Domicile of litigation	The Supreme Court of NY
Allegations	The complaint asserts claims for breach of contract and alleges, among other things, that the loans in the trust, which had an original principal balance of approximately $516 million, breached various representations and warranties.
Damages sought	The complaint seeks, among other relief, unspecified damages, attorneys’ fees, interest and costs.
Wilmington Trust Company v. Morgan Stanley Mortgage Capital Holdings LLC et al. | Maximum
Loss Contingencies
Estimate of possible loss		152
Financial Guaranty Insurance Company v. Morgan Stanley ABS Capital I Inc. et al. (NIMS 2007-1)
Loss Contingencies
Lawsuit filing date	Sep. 19, 2014
Name of plaintiff	Financial Guaranty Insurance Company (“FGIC”)
Name of defendant	The Firm
Domicile of litigation	The Supreme Court of NY
Allegations	The complaint asserts claims for breach of contract and alleges, among other things, that the net interest margin securities (“NIMS”) in the trust breached various representations and warranties. FGIC issued a financial guaranty policy with respect to certain notes that had an original balance of approximately $475 million.
Damages sought	The complaint seeks, among other relief, specific performance of the NIMS breach remedy procedures in the transaction documents, unspecified damages, reimbursement of certain payments made pursuant to the transaction documents, attorneys’ fees and interest.
Financial Guaranty Insurance Company v. Morgan Stanley ABS Capital I Inc. et al. (NIMS 2007-1) | Maximum
Loss Contingencies
Estimate of possible loss		126
Financial Guaranty Insurance Company v. Morgan Stanley ABS Capital I Inc. et al. (Trust 2007-NC4)
Loss Contingencies
Lawsuit filing date	Sep. 23, 2014
Name of plaintiff	FGIC
Name of defendant	The Firm
Domicile of litigation	The Supreme Court of NY
Allegations	The complaint asserts claims for breach of contract and fraudulent inducement and alleges, among other things, that the loans in the trust breached various representations and warranties and defendants made untrue statements and material omissions to induce FGIC to issue a financial guaranty policy on certain classes of certificates that had an original balance of approximately $876 million.
Damages sought	The complaint seeks, among other relief, specific performance of the loan breach remedy procedures in the transaction documents, compensatory, consequential and punitive damages, attorneys’ fees and interest.
Financial Guaranty Insurance Company v. Morgan Stanley ABS Capital I Inc. et al. (Trust 2007-NC4) | Maximum
Loss Contingencies
Estimate of possible loss		277
Deutsche Bank National Trust Company solely in its capacity as Trustee of the Morgan Stanley ABS Capital I Inc. Trust 2007-NC4 v. Morgan Stanley Mortgage Capital Holdings LLC as Successor-by-Merger to Morgan Stanley Mortgage Capital Inc., and Morgan Stanley ABS Capital I Inc.
Loss Contingencies
Lawsuit filing date	Jan. 23, 2015
Name of plaintiff	Deutsche Bank National Trust Company
Name of defendant	The Firm
Domicile of litigation	The Supreme Court of NY
Allegations	The complaint asserts claims for breach of contract and alleges, among other things, that the loans in the trust, which had an original principal balance of approximately $1.05 billion, breached various representations and warranties.
Damages sought	The complaint seeks, among other relief, specific performance of the loan breach remedy procedures in the transaction documents, compensatory, consequential, rescissory, equitable and punitive damages, attorneys’ fees, costs and other related expenses, and interest.
Deutsche Bank National Trust Company solely in its capacity as Trustee of the Morgan Stanley ABS Capital I Inc. Trust 2007-NC4 v. Morgan Stanley Mortgage Capital Holdings LLC as Successor-by-Merger to Morgan Stanley Mortgage Capital Inc., and Morgan Stanley ABS Capital I Inc. | Maximum
Loss Contingencies
Estimate of possible loss		277
Case Number 15/3637 and Case Number 15/4353
Loss Contingencies
Name of plaintiff	The Dutch Tax Authority (“Dutch Authority”)
Name of defendant	The Firm
Domicile of litigation	The District Court in Amsterdam
Allegations	The prior set-off by the Firm of approximately €124 million (approximately $152 million) plus accrued interest of withholding tax credits against the Firm’s corporation tax liabilities for the tax years 2007 to 2013. The Dutch Authority alleges that the Firm was not entitled to receive the withholding tax credits on the basis, inter alia, that a Firm subsidiary did not hold legal title to certain securities subject to withholding tax on the relevant dates. The Dutch Authority has also alleged that the Firm failed to provide certain information to the Dutch Authority and keep adequate books and records.
Case Number 15/3637 and Case Number 15/4353 | Maximum
Loss Contingencies
Estimate of possible loss	€ 124	$ 152