Employee Benefit Plans - Narrative (Details) - USD ($)	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
Pension and Other Postretirement Plans
Proportion of assets as to total pension plan assets (as a percent)		86.00%
Expected contributions by employer in 2021	$ 88,000,000
Morgan Stanley 401(k) Plan
Pension and Other Postretirement Plans
Maximum proportion of employer matching contributions (as a percent)	4.00%	4.00%
Morgan Stanley 401(k) Plan \| Participants of a Certain Compensation Level
Pension and Other Postretirement Plans
Maximum proportion of employer matching contributions (as a percent)	5.00%	5.00%
Morgan Stanley 401(k) Plan \| Eligible U.S. Employees with Eligible Pay Less than or Equal to $100,000
Pension and Other Postretirement Plans
Eligible pay threshold	$ 100,001
Proportion of employer matching contribution of eligible pay (as a percent)	2.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details